Add Opensearch version 2 to unit tests and update Elasticsearch versions

What does this MR do and why?

Changes Opensearch unit tests in CI from version 1.2.4 to the latest version 2.0.0

Screenshots or screen recordings

These are strongly recommended to assist reviewers and reduce the time to merge your change.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

.gitlab/ci/rails.gitlab-ci.yml

@@ -569,26 +569,11 @@ rspec-ee unit pg12:
     - .rails:rules:ee-only-unit
     - .rspec-ee-unit-parallel
 
-rspec-ee unit pg12 es7:
-  extends:
-    - .rspec-ee-base-pg12-es7
-    - .rspec-ee-unit-parallel
-
 rspec-ee unit pg12 es8:
   extends:
     - .rspec-ee-base-pg12-es8
     - .rspec-ee-unit-parallel
 
-rspec-ee unit pg12 opensearch1:
-  extends:
-    - .rspec-ee-base-pg12-opensearch1
-    - .rspec-ee-unit-parallel
-
-rspec-ee unit pg12 opensearch2:
-  extends:
-    - .rspec-ee-base-pg12-opensearch2
-    - .rspec-ee-unit-parallel
-
 rspec-ee unit pg12 minimal:
   extends:
     - rspec-ee unit pg12
@@ -607,26 +592,11 @@ rspec-ee integration pg12:
     - .rails:rules:ee-only-integration
     - .rspec-ee-integration-parallel
 
-rspec-ee integration pg12 es7:
-  extends:
-    - .rspec-ee-base-pg12-es7
-    - .rspec-ee-integration-parallel
-
 rspec-ee integration pg12 es8:
   extends:
     - .rspec-ee-base-pg12-es8
     - .rspec-ee-integration-parallel
 
-rspec-ee integration pg12 opensearch1:
-  extends:
-    - .rspec-ee-base-pg12-opensearch1
-    - .rspec-ee-integration-parallel
-
-rspec-ee integration pg12 opensearch2:
-  extends:
-    - .rspec-ee-base-pg12-opensearch2
-    - .rspec-ee-integration-parallel
-
 rspec-ee integration pg12 minimal:
   extends:
     - rspec-ee integration pg12
@@ -645,26 +615,11 @@ rspec-ee system pg12:
     - .rails:rules:ee-only-system
     - .rspec-ee-system-parallel
 
-rspec-ee system pg12 es7:
-  extends:
-    - .rspec-ee-base-pg12-es7
-    - .rspec-ee-system-parallel
-
 rspec-ee system pg12 es8:
   extends:
     - .rspec-ee-base-pg12-es8
     - .rspec-ee-system-parallel
 
-rspec-ee system pg12 opensearch1:
-  extends:
-    - .rspec-ee-base-pg12-opensearch1
-    - .rspec-ee-system-parallel
-
-rspec-ee system pg12 opensearch2:
-  extends:
-    - .rspec-ee-base-pg12-opensearch2
-    - .rspec-ee-system-parallel
-
 rspec-ee system pg12 minimal:
   extends:
     - rspec-ee system pg12
@@ -773,6 +728,61 @@ rspec-ee system pg11:
     - .rails:rules:default-branch-schedule-nightly--code-backstage-ee-only
     - .rspec-ee-system-parallel
 
+# PG12
+rspec-ee unit pg12 es7:
+  extends:
+    - .rspec-ee-base-pg12-es7
+    - .rspec-ee-unit-parallel
+    - .rails:rules:default-branch-schedule-nightly--code-backstage-ee-only
+
+rspec-ee unit pg12 opensearch1:
+  extends:
+    - .rspec-ee-base-pg12-opensearch1
+    - .rspec-ee-unit-parallel
+    - .rails:rules:default-branch-schedule-nightly--code-backstage-ee-only
+
+rspec-ee unit pg12 opensearch2:
+  extends:
+    - .rspec-ee-base-pg12-opensearch2
+    - .rspec-ee-unit-parallel
+    - .rails:rules:default-branch-schedule-nightly--code-backstage-ee-only
+
+rspec-ee integration pg12 es7:
+  extends:
+    - .rspec-ee-base-pg12-es7
+    - .rspec-ee-integration-parallel
+    - .rails:rules:default-branch-schedule-nightly--code-backstage-ee-only
+
+rspec-ee integration pg12 opensearch1:
+  extends:
+    - .rspec-ee-base-pg12-opensearch1
+    - .rspec-ee-integration-parallel
+    - .rails:rules:default-branch-schedule-nightly--code-backstage-ee-only
+
+rspec-ee integration pg12 opensearch2:
+  extends:
+    - .rspec-ee-base-pg12-opensearch2
+    - .rspec-ee-integration-parallel
+    - .rails:rules:default-branch-schedule-nightly--code-backstage-ee-only
+
+rspec-ee system pg12 es7:
+  extends:
+    - .rspec-ee-base-pg12-es7
+    - .rspec-ee-system-parallel
+    - .rails:rules:default-branch-schedule-nightly--code-backstage-ee-only
+
+rspec-ee system pg12 opensearch1:
+  extends:
+    - .rspec-ee-base-pg12-opensearch1
+    - .rspec-ee-system-parallel
+    - .rails:rules:default-branch-schedule-nightly--code-backstage-ee-only
+
+rspec-ee system pg12 opensearch2:
+  extends:
+    - .rspec-ee-base-pg12-opensearch2
+    - .rspec-ee-system-parallel
+    - .rails:rules:default-branch-schedule-nightly--code-backstage-ee-only
+
 # PG13
 rspec-ee migration pg13:
   extends: