Clarify logging messages for invalid attributes on custom events and logging events

[jtduffy]

A couple of the WARNING messages for invalid attributes imply that the entire transaction or logging event will be ignored if an attribute is invalid. These should be more clear that only the invalid attribute will be dropped.

newrelic-java-agent/newrelic-agent/src/main/java/com/newrelic/agent/service/analytics/InsightsServiceImpl.java

Line 397 in 59f9861

Agent.LOG.log(Level.WARNING, "Custom event [{0}] with invalid attributes key or value of null was reported for a transaction but ignored."

newrelic-java-agent/newrelic-agent/src/main/java/com/newrelic/agent/service/logging/LogSenderServiceImpl.java

Line 537 in 59f9861

Agent.LOG.log(Level.WARNING, "Log event with invalid attributes key or value of null was reported for a transaction but ignored."

The current text is:

Custom event [{0}] with invalid attributes key or value of null was reported for a transaction but ignored. 
Each key should be a String and each value should be a String, Number, or Boolean. Key: {1} / Value: {2}

An improved message would be:

Custom event [{0}] with invalid attributes key or value of null was reported for a transaction. 
This attribute will be ignored. Each key should be a String and each value should be a String, 
Number, or Boolean. Key: {1} / Value: {2}

[workato-integration]

https://new-relic.atlassian.net/browse/NR-373119