Make descriptions static where they are not (#3201)

Since the description of the Meters can be different per Meter, we can run into situations when the description is dynamic/different for different Meter.Ids that share the same name but differ in tags. Some backends do not support different description per time series, so whichever is registered first will be used, and it can be confusing as the description is specific to one set of tag values.

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/jvm/JvmThreadMetrics.java

@@ -71,8 +71,7 @@ public void bindTo(MeterRegistry registry) {
             for (Thread.State state : Thread.State.values()) {
                 Gauge.builder("jvm.threads.states", threadBean, (bean) -> getThreadStateCount(bean, state))
                         .tags(Tags.concat(tags, "state", getStateTagValue(state)))
-                        .description("The current number of threads having " + state + " state")
-                        .baseUnit(BaseUnits.THREADS).register(registry);
+                        .description("The current number of threads").baseUnit(BaseUnits.THREADS).register(registry);
             }
         }
         catch (Error error) {

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/logging/LogbackMetrics.java

@@ -149,24 +149,19 @@ class MetricsTurboFilter extends TurboFilter {
 
     MetricsTurboFilter(MeterRegistry registry, Iterable<Tag> tags) {
         errorCounter = Counter.builder("logback.events").tags(tags).tags("level", "error")
-                .description("Number of error level events that made it to the logs").baseUnit(BaseUnits.EVENTS)
-                .register(registry);
+                .description("Number of events that made it to the logs").baseUnit(BaseUnits.EVENTS).register(registry);
 
         warnCounter = Counter.builder("logback.events").tags(tags).tags("level", "warn")
-                .description("Number of warn level events that made it to the logs").baseUnit(BaseUnits.EVENTS)
-                .register(registry);
+                .description("Number of events that made it to the logs").baseUnit(BaseUnits.EVENTS).register(registry);
 
         infoCounter = Counter.builder("logback.events").tags(tags).tags("level", "info")
-                .description("Number of info level events that made it to the logs").baseUnit(BaseUnits.EVENTS)
-                .register(registry);
+                .description("Number of events that made it to the logs").baseUnit(BaseUnits.EVENTS).register(registry);
 
         debugCounter = Counter.builder("logback.events").tags(tags).tags("level", "debug")
-                .description("Number of debug level events that made it to the logs").baseUnit(BaseUnits.EVENTS)
-                .register(registry);
+                .description("Number of events that made it to the logs").baseUnit(BaseUnits.EVENTS).register(registry);
 
         traceCounter = Counter.builder("logback.events").tags(tags).tags("level", "trace")
-                .description("Number of trace level events that made it to the logs").baseUnit(BaseUnits.EVENTS)
-                .register(registry);
+                .description("Number of events that made it to the logs").baseUnit(BaseUnits.EVENTS).register(registry);
     }
 
     @Override