GH-5470: Avoid nested query in JdbcStepExecutionDao.getLastStepExecution

[arimu1]

Fixes #5470

JdbcStepExecutionDao.getLastStepExecution previously called
jobExecutionDao.getJobParameters (a second JDBC statement) while a
ResultSet opened with setMaxRows(1) was still active. On databases
that refuse multiple simultaneously open portals (notably CockroachDB),
that nested prepare fails and restarts break whenever a prior
StepExecution exists for the same job instance and step name.

Changes

• Select only STEP_EXECUTION_ID for the “last step execution” lookup
• Keep portable statement.setMaxRows(1) (no SQL LIMIT, which is not
  supported by all databases Spring Batch targets)
• After that statement completes and is closed by JdbcTemplate, load
  the full StepExecution via getStepExecution(long)

This matches the sequential approach suggested in the issue and the
workaround of reading the id first then delegating to
getStepExecution(long).

Note: open PR #5133 still performs getJobExecution inside the open
ResultSet callback, so it does not address GH-5470.

Testing

• JdbcStepExecutionDaoTests (6 tests, including new coverage for same-job
  and cross-job-execution “last step” selection)
• ./mvnw -pl spring-batch-core -am test -Dtest=JdbcStepExecutionDaoTests
• JDK: Eclipse Temurin 25 (project requires 17; NullAway on this branch needs 22+)

[arimu1]

Follow-up for the portal-completion case called out in #5470:

Nesting alone was not enough. setMaxRows(1) can leave a suspended portal (PortalSuspended rather than CommandComplete) on pgjdbc-style wire protocol, so a subsequent prepare still fails on CockroachDB even after the Java ResultSet is closed.

This push:

• drops statement.setMaxRows(1) on the id-only lookup
• keeps portable ORDER BY SE.CREATE_TIME DESC, SE.STEP_EXECUTION_ID DESC (no SQL LIMIT)
• reads only the first ordered row in Java, lets the statement complete, then loads via getStepExecution(long)
• documents why default fetch size + first-row consumption is acceptable for large history

JdbcStepExecutionDaoTests: 6/6 pass.