Tracking Issue: Fix Sqlsmith workarounds / refinements / bugs

[kwannoel]

Several features are currently not fully supported, hence some parts of sqlsmith are disabled, or use workarounds. We should re-enable them when their dependent issues are fixed.

Bugs:

• [x] #4220
• [x] #4344
• [x] #4434
• [ ] #4508
• [ ] #3908

Workarounds:

• [x] #4057
• [x] #3935
• [x] #3939 workaround: #3929
• [x] #3900 workaround: #3929
• [x] #4058
• [ ] #3908 workaround: #3956
• [ ] #4737
  • [x] #4220
• [x] #4024
• [ ] Enable gen_limit for materialized view.

Refinements - Query Generator:

• [x] Look into gen_agg_expr, simplify if possible.
• [x] Clean up docstrings for various functions.
• [x] #4056
• [x] #4068
• [x] #4059
• [x] #4002
• [x] #4065
• [x] #4086
• [x] #4002
• [ ] #3936
• [x] #3964
• [ ] Revisit gen_from_relation's use of can_recurse. Other branches might recurse in the future. See: https://github.com/singularity-data/risingwave/pull/4216/files#r934137424
• [ ] #4295
• [ ] #4296
• [ ] Refine recursion so that probability of recursion drop with increasing depth of recursion See: https://github.com/singularity-data/risingwave/pull/4216#discussion_r934130194
• [ ] Generate select with no tables select *;.
• [ ] #4468
• [ ] Generate other table functions: generate_series, unnest. See: https://github.com/singularity-data/risingwave/issues/4540
• [ ] Generate cast implicit via concat/concat_ws.
• [ ] Generate more complex Time Window Functions: e.g. Different window slide.
• [ ] Enable gen non-positive intervals for non Time Window Functions.
• [ ] Enable gen array_agg.

Refinements - Test suite:

• [ ] Reduce runtime of e2e sqlsmith, profile which queries are taking a long time to execute.
• [ ] #4415
• [ ] Query shrinking to debug complex queries

Related: #2571