[operator, monitor] Correctly close response when posting to the sessions' backend

[kittaakos]

Describe the bug

The response is not closed after pinging the session:

theia-cloud/java/operator/org.eclipse.theia.cloud.operator/src/main/java/org/eclipse/theia/cloud/operator/messaging/MonitorMessagingServiceImpl.java

Line 86 in 55813e2

client.newCall(postRequest).execute();

Expected behavior

try (var response = client.newCall(request).execute()) {
    // Maybe handle !response.isSuccessful()?
} catch (IOException e) {
    LOGGER.info("[{}] Could not send message to extension: {}", session.getSpec().getName(), e);
}

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Bonus, one OkHttpClient is created per app lifecycle, not one per request:

theia-cloud/java/operator/org.eclipse.theia.cloud.operator/src/main/java/org/eclipse/theia/cloud/operator/messaging/MonitorMessagingServiceImpl.java

Line 73 in 55813e2

OkHttpClient client = new OkHttpClient().newBuilder().build();

---

Maybe log the !response.isSuccessful() case?

Cluster provider

No response

Version

No response

Additional information

Update:
Same issue in

theia-cloud/java/operator/org.eclipse.theia.cloud.operator/src/main/java/org/eclipse/theia/cloud/operator/plugins/MonitorActivityTracker.java

Line 155 in 83c8f60

client.newCall(postRequest).execute();

[github-actions]

This issue is stale because it has been open for 180 days with no activity.