Build Pulsar on JDK11 - keep binary compatibility with JDK8

[eolivelli]

This is an umbrella issue about moving the build of Pulsar to JDK11.

The outcome of this work will be to switch the development on Pulsar to JDK11, but the binary artifacts produced by the build will be 100% compatible with JDK8.
So users will be able to run the server side on JDK8 and to use JDK8 in order to run the Java client.

At the end of this work:

• You can build Pulsar on JDK11
• Tests pass on JDK11
• Docker images will be switched to JDK11

This issue is not about removing the support to JDK11, and in fact most of the work will be in the direction of keeping the compatibility with JDK8 even while working on JDK11

List of issues/PRs on JDK11:

• [jdk11] Test failure KeyStoreTlsProducerConsumerTestWithAuth on JDK11: Received fatal alert: handshake_failure #9720
• [jdk11] Avro tests fail on JDK11 #10122
• Fix some ExecutorService leaks #10198
• [Tests] Recreate keystores used in TLS tests with RSA key algorithm & SHA256 to support JDK 11 & TLS 1.3 #10336
• [Build] Fix core-modules profile on JDK11 #10340
• [Tests] Fix KeyStoreTlsTest on JDK11 #10345
• [Pulsar SQL] Fix Presto startup on JDK11 #10559
• [Tests] Fix test retries for Pulsar Functions integration tests #10565
• [Tests] Add workaround for failing PulsarFunctionsJavaProcessTest on JDK11 #10566
• Switch to use JDK11 for CI and Docker images #10580

This is a test PR that runs tests on JDK11 on @eolivelli fork
eolivelli#6

[lhotari]

This PR fixes the binary compatibility so that binary compiled with JDK11 are compatible with JDK8 at runtime: #10343

[lhotari]

Configuring Jetty to use Conscrypt/OpenSSL will fix some JDK11 issues, #10372 .
It fixes BrokerServiceTest#testTlsAuthDisallowInsecure and SuperUserAuthedAdminProxyHandlerTest#testAuthWithRandoCert.

[codelipenghui]

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