Remove font weight 100 and 300

What does this MR do and why?

Related #463757 (closed)

Remove font weight 100 and 300 (there are only 3 occurrences and these have bad legibility/accessibility)

• Remove font weight 100 from job group dropdown
• Remove font weight 300 from new vulnerability form cvss label
• Remove font weight 300 from pre scan verification status label

with these 2 variants gone, we'll only have .gl-font-weight-normal, .gl-font-weight-semibold, and .gl-font-weight-bold to migrate for tailwind, see #456641 (closed)

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

Prerequisites

1. You need an EE license
2. You need to have runners enabled (See $2408961 for setting up a runner)
3. Import https://gitlab.com/lorenzvanherwaarden/security-reports-with-parallel-job (not the standard security-reports example repo)
4. Run a pipeline on master

CVSS

1. Apply patch by copying this patch and executing pbpaste | git apply

diff --git a/ee/app/assets/javascripts/vulnerabilities/components/new_vulnerability/section_details.vue b/ee/app/assets/javascripts/vulnerabilities/components/new_vulnerability/section_details.vue
index b953f67d4b1b..6e680a584bb4 100644
--- a/ee/app/assets/javascripts/vulnerabilities/components/new_vulnerability/section_details.vue
+++ b/ee/app/assets/javascripts/vulnerabilities/components/new_vulnerability/section_details.vue
@@ -34,7 +34,7 @@ export default {
       // is still missing. Since I learned this after implementing the design, I decided to
       // hide it from the UI until the backend is ready so that we don't lose the work
       // already completed.
-      showCvss: false,
+      showCvss: true,
       cvss: '',
       statusId: '',
       severity: '',

2. Go to http://gdk.test:3000/gitlab-org/security-reports-with-parallel-job/-/security/vulnerabilities/new
3. Validate that "(optional)" is shown in normal font weight (by using optional prop for GlFormGroup.

Job group dropdown

1. Go to http://gdk.test:3000/gitlab-org/security-reports-with-parallel-job/-/pipelines and click on the latest pipeline
2. Validate that the number "2" next to the container scanning job has normal font weight

Pre scan validation status

1. Enable dast_pre_scan_verification feature flag, by going to http://gdk.test:3000/rails/features
2. Go to http://gdk.test:3000/gitlab-org/security-reports-with-parallel-job/-/security/configuration
3. Click "Configure DAST"
4. Validate that "(optional)" next to "Pre-scan verification" has normal font weight