[SNOW-1694712] Remove _emit_ast and _ast from docs.

[sfc-gh-lspiegelberg]

1. Which Jira issue is this PR addressing? Make sure that there is an accompanying issue to your PR.
   FixesSNOW-1694712

2. Fill out the following pre-review checklist:

   • I am adding a new automated test(s) to verify correctness of my new code
     • If this test skips Local Testing mode, I'm requesting review from @snowflakedb/local-testing
   • I am adding new logging messages
   • I am adding a new telemetry message
   • I am adding new credentials
   • I am adding a new dependency
   • If this is a new feature/behavior, I'm adding the Local Testing parity changes.
   • I acknowledge that I have ensured my changes to be thread-safe. Follow the link for more information: Thread-safe Developer Guidelines

3. Please describe how your code solves the related issue.

   AST introduces in function signatures (private) parameters _emit_ast and _ast. This PR modifies the sphinx-build to not emit these parameters into the docs. To check that the generation is successful, run e.e. from the docs folder

grep -rl --include "*.html" "_emit_ast" build/html
grep -rl --include "*.html" "_ast" build/html

[sfc-gh-aalam]

can you look at these formatting issues where we see double closed parenthesis

[sfc-gh-aalam]

there are similar issues I noticed in column and dataframe

[sfc-gh-aling]

pre-approving, assuming you will address Afroz's comment