Add keepalive to responseInputStream timeout scheduler executor to ma…

[RanVaknin]

Addresses: #6567

Background and context

ResponseInputStream uses a static ScheduledExecutorService to abort streams that aren't read within 60 seconds (to prevent connection leaks). The executor's thread never terminates because core threads are kept alive indefinitely by default. This causes the response-input-stream-timeout-scheduler thread to persist for the lifetime of the JVM, even when no streams exist.

To fix this, we can set allowCoreThreadTimeOut(true) and a 60s keep-alive on the executor. The thread now dies after 60 seconds of idleness and respawns on demand (matches TransferManagerConfiguration.java).

Testing

Since there is a timeout and a keep alive mechanism it's hard to write a deterministic test to prove the fix works. Additionally, adding a test with a sleep method of >1min is not feasible.
The following test fails on Master, and passes after the code change introduced in the PR:

    @Test
    void schedulerThread_shouldTerminateAfterIdleTimeout() throws Exception {
        ResponseInputStream<Object> responseInputStream = responseInputStream(Duration.ofSeconds(1));
        responseInputStream.read();
        responseInputStream.close();

        Thread.sleep(65000);

        Set<String> schedulerThreads = new HashSet<>();

        for (Thread thread : Thread.getAllStackTraces().keySet()) {
            if (thread.getName().contains("response-input-stream-timeout-scheduler")) {
                schedulerThreads.add(thread.getName());
            }
        }
        assertThat(schedulerThreads).isEmpty();
    }

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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