Change PG to 13 for pipelines

What does this MR do and why?

We can upgrade the PG to version 13 in pipelines as confirmed with SRE that we are using PG 13 on SaaS.

Failure #1 PG12 ERROR

change it to PG13

Upstream is using PG14, and they are also has this error in their pipelines with PG 12, like this one https://gitlab.com/gitlab-org/gitlab/-/jobs/5386376450.

Errors on PG 12 https://jihulab.com/gitlab-cn/gitlab/-/jobs/11161325

Created database 'gitlabhq_test'
Created database 'gitlabhq_test_ci'
psql:/builds/gitlab-cn/gitlab/db/structure.sql:36785: ERROR:  "p_ci_builds" is a partitioned table
DETAIL:  Partitioned tables cannot have BEFORE / FOR EACH ROW triggers.
rake aborted!
failed to execute:
psql --set ON_ERROR_STOP=1 --quiet --no-psqlrc --output /dev/null --file /builds/gitlab-cn/gitlab/db/structure.sql --single-transaction gitlabhq_test

Please check the output above for any errors and make sure that `psql` is installed in your PATH and has proper permissions.

Failure #2 user_merges_merge_request_spec.rb

https://jihulab.com/gitlab-cn/gitlab/-/jobs/11163579

add refresh and change the selector to make sure it changes the value at least.

Failure #3 ee/spec/features/dashboard/navbar_spec.rb:35

https://jihulab.com/gitlab-cn/gitlab/-/jobs/11165563

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How to set up and validate locally

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

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