chore: include docs build scripts in pipeline + fix scripts

[jakovljevic-mladen]

Description: To avoid issues that we had multiple times so far where the docs build was broken after some PR merges, I'm adding running docs build and generation scripts to the pipelines. This only runs setup and build scripts from the docs_app, it does not deploy app remotely.

Related issue (if exists): None, but one of the latest issue we had was fixed in #6881. We want to avoid having such PRs by including these runs. Also, running current build script will fail pipelines until #6912 is merged.

[benlesh]

Let me know if you need anything for this.

[jakovljevic-mladen]

Changes from the commit 1685d86 were suggested by this comment.

[jakovljevic-mladen]

Let me know if you need anything for this.

Thanks @benlesh, I somehow managed to fix everything. This PR is ready for review. @kwonoj, can you please review this PR as well?

[benlesh]

@jakovljevic-mladen feel free to merge these into 7.x and master as you please.

[jakovljevic-mladen]

Cherry-picked to 7.x.

One note: changes from this PR only will now include running setup and build scripts from the docs_app. The result of this action will not be used to automatically deploy the docs app to our official docs site. This will be useful to avoid having a follow-up PR that fix docs-app related issues that could have been avoided if this step was included in the original PRs.