Add possibility to specify local testcontainer parameters for integration tests.

[sothawo]

Currently on my macOS 15.3 with M4 silicon chip the Elasticsearch docker container crashes (the JVM) in there. This is a known bug in OpenJDK. Until this is fixed I need to add these entries to the environment:

• CLI_JAVA_OPTS=-XX:UseSVE=0
• ES_JAVA_OPTS=-XX:UseSVE=0

In order to not have this on other machines, these values should go into a testcontainers-local.properties file which is git-ignored.