[Test] Unmute fixed tests (elastic#120687)

These tests should have been unmuted as part of the fixing PR elastic#120581.

Relates: elastic#120581

Author: ywangd

muted-tests.yml

@@ -224,14 +224,6 @@ tests:
   issue: https://github.com/elastic/elasticsearch/issues/120482
 - class: org.elasticsearch.xpack.sql.expression.function.scalar.datetime.DateTimeToCharProcessorTests
   issue: https://github.com/elastic/elasticsearch/issues/120575
-- class: org.elasticsearch.discovery.ec2.DiscoveryEc2KeystoreCredentialsIT
-  issue: https://github.com/elastic/elasticsearch/issues/120576
-- class: org.elasticsearch.discovery.ec2.DiscoveryEc2KeystoreSessionCredentialsIT
-  issue: https://github.com/elastic/elasticsearch/issues/120577
-- class: org.elasticsearch.discovery.ec2.DiscoveryEc2SystemPropertyCredentialsIT
-  issue: https://github.com/elastic/elasticsearch/issues/120578
-- class: org.elasticsearch.discovery.ec2.DiscoveryEc2EnvironmentVariableCredentialsIT
-  issue: https://github.com/elastic/elasticsearch/issues/120579
 - class: org.elasticsearch.action.search.SearchProgressActionListenerIT
   method: testSearchProgressWithHitsAndAggs
   issue: https://github.com/elastic/elasticsearch/issues/120583