Bug: Postsvc Tests

[appins]

Postsvc tests (https://github.com/OpenEugene/openboard/blob/main/back/tests/openbsrv/postsvc_test.go) are a little broken.

Issues:

• Tests cannot be run in any order and depend on the results of the tests that were run before them.
• Tests that use the find posts request do not actually check which post(s) are being returned (https://github.com/OpenEugene/openboard/blob/main/back/tests/openbsrv/postsvc_test.go#L166).
• Some tests do not check if there are unintended side effects (https://github.com/OpenEugene/openboard/blob/main/back/tests/openbsrv/postsvc_test.go#L154 would edit posts and only check the post that was edited).