Change level of initialization exception to error, make errors obvious

[bvolpato]

Exceptions in JvmInitializers were being printed in the STDOUT by the FnHarness, so handled/displayed on Dataflow as an info log:

This change should help making errors more obvious, and allow users to leverage Error Reporting.

I still kept e.printStackTrace(); in case there was someone relies on looking at errors on STDOUT/STDERR (happy to remove if seen as a bad practice).

[github-actions]

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[Abacn]

I would agree to preserve the printStackTrace line. In case log client is unavailable there is possibility that log4j logs are not get printed. Then System.out or System.err would still be useful

[bvolpato]

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