Bug: index worker logging broken

[artntek]

we noticed when deploying 3.1.0 that logging did not work, and saw only this in the index worker logs:

SLF4J(W): No SLF4J providers were found.
SLF4J(W): Defaulting to no-operation (NOP) logger implementation
SLF4J(W): See https://www.slf4j.org/codes.html#noProviders for further details.
SLF4J(W): Class path contains SLF4J bindings targeting slf4j-api versions 1.7.x or earlier.
SLF4J(W): Ignoring binding found at [jar:file:/var/lib/dataone-indexer/dataone-index-worker-3.1.0-shaded.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J(W): See https://www.slf4j.org/codes.html#ignoredBindings for an explanation.

Since logging worked in the version of indexer bundled with metacat (metacat/metacat-index), we copied the logging dependencies from the metacat-index pom file to the indexer pom file. This resulted in a different log message:

log4j:WARN No appenders could be found for logger (org.dataone.cn.indexer.IndexWorker).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

We resolved it by removing any log4j v1 dependencies (namely the slf4j-log4j12 dependency), and also renamed the k8s mount-point for the log4j properties file from log4j.properties to log4j2.properties