fix: EXPOSED-133 Suspend transactions blocking Hikari connection pool

[bog-walk]

If the maximumPoolSize of a HikariDataSource is exceeded, any active connections made through newSuspendedTransaction() are not released back into the pool after job completion. This leads to a connection timeout exception when attempting to get more connections.

resetIfClosed(), invoked in suspendedTransactionAsyncInternal(), calls getConnection() to check if a transaction is closed (may happen after a repetition attempt fails), so that it can be properly reset for another attempt. This blocks the connections being released.

The function was introduced in PR #1774 and should not be necessary for the first loop, as the transaction is created with an open connection.

Now resetIfClosed() is only called on subsequent repetition attempt loops.

Unit test:

• No unit test has been included as it would require including a permanent dependency on Hikari CP in the exposed-tests module.
• To test on the branch, include the following in exposed-tests/build.gradle.kts, before running the test provided in the original YT issue:

implementation("com.zaxxer:HikariCP:5.0.1")
implementation("com.h2database", "h2", Versions.h2)
// compileOnly("com.h2database", "h2", Versions.h2)

[e5l]

I would add h2 dependency in exposed-tests to make a test, it's not a published module so it should be fine

[bog-walk]

@e5l Switching h2 dependency from compileOnly to implementation causes a build fail on multiple tests in exposed-java-time, so that dependency hasn't been changed.

A dependency on Hikari CP was still included with a new unit test by letting HikariDataSource resolve the H2 driver itself instead of configuring driverClassName.