Modified the Java agent to leave any existing labels on a breakpoint un-changed and only add in new labels it wants to record. If a Java agent label name conflicts with a pre existing label name, the pre existing label has priority and it will not be modified.
Modified the Java agent to leave any existing labels on a breakpoint un-changed and only add in new labels it wants to record. If a Java agent label name conflicts with a pre existing label name, the pre existing label has priority and it will not be modified.

PiperOrigin-RevId: 242115483
Change-Id: I7fdd5856df98b73642d6d18679c912442f83130c

GoogleCloudPlatform/cloud-debug-java,GoogleCloudPlatform/cloud-debug-java,GoogleCloudPlatform/cloud-debug-java,GoogleCloudPlatform/cloud-debug-java