Docs rli bug

[cosmicBboy]

Why are the changes needed?

Code snippets using the rli directive aren't rendering in the docs: https://docs.flyte.org/en/latest/user_guide/basics/hello_world.html

The root cause is that the readthedocs build server gets 403 errors when trying to get files from github

https://app.readthedocs.org/projects/flyte/builds/26258764/

/home/docs/checkouts/readthedocs.org/user_builds/flyte/checkouts/latest/docs/user_guide/testing/mocking_tasks.md:10017: WARNING: HTTP request returned error code 403
--
1112 | /home/docs/checkouts/readthedocs.org/user_builds/flyte/checkouts/latest/docs/user_guide/testing/mocking_tasks.md:10024: WARNING: HTTP request returned error code 403
1113 | /home/docs/checkouts/readthedocs.org/user_builds/flyte/checkouts/latest/docs/user_guide/testing/mocking_tasks.md:10031: WARNING: HTTP request returned error code 403
1114 | /home/docs/checkouts/readthedocs.org/user_builds/flyte/checkouts/latest/docs/user_guide/testing/mocking_tasks.md:10038: WARNING: HTTP request returned error code 403
1115 | /home/docs/checkouts/readthedocs.org/user_builds/flyte/checkouts/latest/docs/user_guide/testing/mocking_tasks.md:10045: WARNING: HTTP request returned error code 403

What changes were proposed in this pull request?

Since we're already pulling in content from flytesnacks for the integrations and tutorials, we can just use literalinclude instead of rli to render the code snippets.

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 36.95%. Comparing base (f20b8aa) to head (069501e).
Report is 5 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6008   +/-   ##
=======================================
  Coverage   36.95%   36.95%           
=======================================
  Files        1310     1310           
  Lines      131464   131464           
=======================================
+ Hits        48587    48588    +1     
+ Misses      78656    78655    -1     
  Partials     4221     4221           

Flag	Coverage Δ
unittests-datacatalog	51.58% <ø> (ø)
unittests-flyteadmin	54.07% <ø> (ø)
unittests-flytecopilot	22.23% <ø> (ø)
unittests-flytectl	62.39% <ø> (ø)
unittests-flyteidl	6.95% <ø> (ø)
unittests-flyteplugins	53.83% <ø> (ø)
unittests-flytepropeller	43.10% <ø> (ø)
unittests-flytestdlib	55.31% <ø> (+0.01%)	⬆️

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