Misc Annoy index improvements

[rschu1ze]

A mixed bag of fixes for Annoy:

• tests:
  • added tests with different GRANULARITY-s.
  • re-enabled tests which were disabled (Temporarily disable annoy index tests (flaky for analyzer) #50714) due to flakiness in analyzer tests
  • commented out tests with unstable results. This was caused by the inherent randomness of Annoy search. They are useful anyways, so don't remove them completely.
• much more extensive docs
• changed the default GRANULARITY of Annoy indexes from 1 to 100 million rows. This is much closer to the behavior users intuitively expect

Changelog category (leave one):

• Not for changelog (changelog entry is not required)

[robot-clickhouse-ci-2]

This is an automated comment for commit 7745f7d with description of existing statuses. It's updated for the latest CI running
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The overall status of the commit is 🟡 pending

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[rschu1ze]

ClickHouse Stateless Tests (debug) [4/5]:

• 01605_adaptive_granularity_block_borders 01605_adaptive_granularity_block_borders is flaky #50681

ClickHouse Stateless Tests (msan) [3/6]

• 00534_functions_bad_arguments12 00534_functions_bad_arguments tests are flaky #50619
• 00534_functions_bad_arguments4_long 00534_functions_bad_arguments tests are flaky #50619

[devcrafter]

@rschu1ze Please check the comments regarding the tests. It's up to you when address them, if at all

[rschu1ze]

@devcrafter Very good comments, thanks. I'd look into them separately. For now, allow me to merge - someone is waiting for the updated docs and I don't want to point to an open PR.

[rfraposa]

Just FYI: this PR has broken the build of the docs. I am going to try and fix the issue in a separate PR.

[devcrafter]

@devcrafter Very good comments, thanks. I'd look into them separately. For now, allow me to merge - someone is waiting for the updated docs and I don't want to point to an open PR.

@rschu1ze Please add me as a reviewer to follow-up PRs

[rschu1ze]

Just FYI: this PR has broken the build of the docs. I am going to try and fix the issue in a separate PR.

Sorry for the hassle (I was pretty sure that the docs check was green).

@rschu1ze Please add me as a reviewer to follow-up PRs

Will do, here is one: #50912 ... more are coming.

[rfraposa]

No hassle at all...happy to fix it. Docusaurus uses React and it gets confused when it sees something like <ann_index_name>. I just replaced the angle brackets with square brackets: #50942