[790101] - as5 plugin: warnings should not be logged for AS/EAP versions that do not require the corresponding jar
I changed the offensive WARN-level message to DEBUG level.  It's not really
possible to distinguish between non-existent and non-readable, or to know
which versions require which JAR.  If there is a failure then we can turn
on debug to see the message.

Cherry-Pick master bed4b9a72f3f6ec19939e82a9fd27e392dc85a9c