[15.0] bugfixes: collection of fixes to bugs found while fuzzing

[systay]

Description

Fixes three one-line issues.

1. Join predicates on outer joins that only depend on the RHS of the join turns join into an inner join
2. Projection not handling types correctly would fail some aggregation queries
3. Filter checking if values are 1 instead of using MySQLs coercion to bool

Related Issue(s)

This was found with automated query fuzzing (#13279)
Backport of #13332

Checklist

• "Backport to:" labels have been added if this change should be back-ported
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on the CI
• Documentation was added or is not required

[vitess-bot]

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