sql, jobs: stop queuing schema change jobs for in-txn schema changes

[postamar]

Creating a table and changing its schema within a transaction would
cause a schema change job to be queued. Such jobs are not necessary and
don't do anything. This patch prevents them from being queued in the
first place.

Fixes #45985.

Release note (sql change): Creating a table and changing its schema
within a transaction no longer schedules a schema change job.

[cockroach-teamcity]

This change is 

[ajwerner]

Reviewed 2 of 2 files at r1.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @postamar)

---

pkg/sql/logictest/testdata/logic_test/alter_table, line 1508 at r1 (raw file):

query I
SELECT count(*) FROM [SHOW JOBS] WHERE job_type = 'SCHEMA CHANGE' AND description LIKE 'ALTER TABLE test.public.t45985 %'

This is potentially brittle because these strings might change. What about:

SELECT count(descriptor_id)
  FROM (
        SELECT json_array_elements_text(
                crdb_internal.pb_to_json(
                    'cockroach.sql.jobs.jobspb.Payload',
                    payload
                )->'descriptorIds'
               )::INT8 AS descriptor_id
          FROM system.jobs
       )
 WHERE descriptor_id = ('test.public.t45985'::REGCLASS)::INT8;

[postamar]

Reviewable status: complete! 0 of 0 LGTMs obtained (and 1 stale) (waiting on @ajwerner)

---

pkg/sql/logictest/testdata/logic_test/alter_table, line 1508 at r1 (raw file):

Previously, ajwerner wrote…

This is potentially brittle because these strings might change. What about:

SELECT count(descriptor_id)
  FROM (
        SELECT json_array_elements_text(
                crdb_internal.pb_to_json(
                    'cockroach.sql.jobs.jobspb.Payload',
                    payload
                )->'descriptorIds'
               )::INT8 AS descriptor_id
          FROM system.jobs
       )
 WHERE descriptor_id = ('test.public.t45985'::REGCLASS)::INT8;

Done.

[postamar]

CI failed due to an unrelated test failure for which there is already an issue open: #58989

[postamar]

bors r+

[craig]

Build succeeded:

• GitHub CI (Cockroach)