Pin TLS1.2 in SSLConfigurationReloaderTests

Ensure that the SSLConfigurationReloaderTests can run with JDK 11
by pinning the HttpClient to TLS version to TLS1.2. This is necessary
becase even if the MockWebServer is set to user TLS1.2, we don't
set its enabled protocols, so if it receives a TLS1.3 request (which
is the default behavior for HttpClient in JDK11), it will use TLS1.3
and the original issue will manifest again.

Relates  elastic#33127
Resolves elastic#32124

Author: jkakavas

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ssl/SSLConfigurationReloaderTests.java

@@ -510,7 +510,7 @@ private static CloseableHttpClient getSSLClient(Path trustStorePath, String trus
         try (InputStream is = Files.newInputStream(trustStorePath)) {
             trustStore.load(is, trustStorePass.toCharArray());
         }
-        final SSLContext sslContext = new SSLContextBuilder().loadTrustMaterial(trustStore, null).build();
+        final SSLContext sslContext = new SSLContextBuilder().useProtocol("TLSv1.2").loadTrustMaterial(trustStore, null).build();
         return HttpClients.custom().setSSLContext(sslContext).build();
     }
 
@@ -527,7 +527,7 @@ private static CloseableHttpClient getSSLClient(List<Path> trustedCertificatePat
         for (Certificate cert : CertParsingUtils.readCertificates(trustedCertificatePaths)) {
             trustStore.setCertificateEntry(cert.toString(), cert);
         }
-        final SSLContext sslContext = new SSLContextBuilder().loadTrustMaterial(trustStore, null).build();
+        final SSLContext sslContext = new SSLContextBuilder().useProtocol("TLSv1.2").loadTrustMaterial(trustStore, null).build();
         return HttpClients.custom().setSSLContext(sslContext).build();
     }