Allow full path search for "/projects/:id/share_locations" API endpoint

What does this MR do and why?

Fixes #393439 (closed).

The service used to fetch Group records for the /projects/:id/share_locations endpoint did not allow for searching with full group paths, which is what this MR fixes.

Added more detail as inline comment.

Query plans

as admin, https://gitlab.com/api/v4/projects/278964/share_locations?search=gitlab-gold/briecarranza/experimental/306349

SELECT "namespaces".* FROM "namespaces" WHERE "namespaces"."type" = 'Group' AND "namespaces"."type" != 'Project' AND "namespaces"."id" IN (SELECT "routes"."source_id" FROM "routes" WHERE "routes"."source_type" = 'Namespace' AND ("routes"."path" ILIKE '%gitlab-gold/briecarranza/experimental/306349%' OR "routes"."name" ILIKE '%gitlab-gold/briecarranza/experimental/306349%')) ORDER BY "namespaces"."path" ASC, "namespaces"."id" ASC LIMIT 20 OFFSET 0

Query plan: https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/15984/commands/55116

as non-admin, https://gitlab.com/api/v4/projects/278964/share_locations?search=gitlab-gold/briecarranza/experimental/306349, user manojmj

WITH RECURSIVE "base_and_descendants" AS ((SELECT "namespaces".* FROM "namespaces" INNER JOIN "members" ON "namespaces"."id" = "members"."source_id" WHERE "members"."type" = 'GroupMember' AND "members"."source_type" = 'Namespace' AND "namespaces"."type" = 'Group' AND "members"."user_id" = 4093067 AND "members"."requested_at" IS NULL AND (access_level >= 10) AND (members.access_level >= 10))
UNION
(SELECT "namespaces".* FROM "namespaces", "base_and_descendants" WHERE "namespaces"."type" = 'Group' AND "namespaces"."parent_id" = "base_and_descendants"."id")) SELECT "namespaces".* FROM "base_and_descendants" AS "namespaces" WHERE "namespaces"."type" != 'Project' AND "namespaces"."id" IN (SELECT "routes"."source_id" FROM "routes" WHERE "routes"."source_type" = 'Namespace' AND ("routes"."path" ILIKE '%gitlab-gold/briecarranza/experimental/306349%' OR "routes"."name" ILIKE '%gitlab-gold/briecarranza/experimental/306349%')) ORDER BY "namespaces"."path" ASC, "namespaces"."id" ASC LIMIT 20 OFFSET 0

Query plan: https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/15984/commands/55120

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Related to #393439 (closed)