Target Android API 21 with animalsniffer and disable it for metrics for now since it's unstable. (open-telemetry#2809)

Author: Anuraag Agrawal

build.gradle.kts

@@ -372,7 +372,7 @@ subprojects {
 
         plugins.withId("ru.vyarus.animalsniffer") {
             dependencies {
-                add(AnimalSnifferPlugin.SIGNATURE_CONF, "com.toasttab.android:gummy-bears-api-24:0.3.0:coreLib@signature")
+                add(AnimalSnifferPlugin.SIGNATURE_CONF, "com.toasttab.android:gummy-bears-api-21:0.3.0:coreLib@signature")
             }
 
             configure<AnimalSnifferExtension> {

sdk/metrics/build.gradle.kts

@@ -3,7 +3,10 @@ plugins {
     id("maven-publish")
 
     id("me.champeau.gradle.jmh")
-    id("ru.vyarus.animalsniffer")
+
+    // TODO(anuraaga): Enable animalsniffer by the time we are getting ready to release a stable
+    // version. Long/DoubleAdder are not part of Android API 21 which is our current target.
+    // id("ru.vyarus.animalsniffer")
 }
 
 description = "OpenTelemetry SDK Metrics"