Pipeline validation errors log at WARN level

[damccorm]

Validation errors mean the pipeline can't be run, so we should log at ERROR.

beam/runners/java-fn-execution/src/main/java/org/apache/beam/runners/fnexecution/jobsubmission/InMemoryJobService.java

Line 225 in 072dd4b

LOG.warn("Encountered Unexpected Exception during validation", e);

Imported from Jira BEAM-9772. Original Jira may contain additional context.
Reported by: ibzib.