Summary:
ASAN reported memory leaks in anon.c due to memory being allocated
using malloc and not being freed. This diff frees the memory allocated
by malloc wherever possible, and uses palloc otherwise.

The pallocs are used in `pa_masking_value_for_att`, and
they are palloced in the same memory context, and the
other one has no indication of being explicitly freed (for
example, `pa_masking_expressions_for_table(...)` is not
pfreed in `pa_masking_stmt_for_table`), so there is already
a precedent of allocating such strings and relying on
memory context free.

Also, org.yb.pgsql.TestPgRegressThirdPartyExtensionsPostgresqlAnonymizer.schedule2
times out on TSAN, so this diff moves some of the tests in schedule 2
to a newly created schedule 3.
Jira: DB-15244

Test Plan:
./yb_build.sh asan --java-test TestPgRegressThirdPartyExtensionsPostgresqlAnonymizer
./yb_build.sh tsan --java-test TestPgRegressThirdPartyExtensionsPostgresqlAnonymizer

Reviewers: jason

Reviewed By: jason

Subscribers: svc_phabricator, hbhanawat, yql

Differential Revision: https://phorge.dev.yugabyte.com/D41654