Disable errorprone RequestExplicitNullMarking

Currently not causing failures, but spamming warnings.

Ported from open-telemetry/opentelemetry-java#7890

Author: trask

buildSrc/src/main/kotlin/otel.errorprone-conventions.gradle.kts

@@ -79,6 +79,7 @@ tasks {
 
         // Requires adding compile dependency to JSpecify
         disable("AddNullMarkedToPackageInfo")
+        disable("RequireExplicitNullMarking")
 
         if (name.contains("Jmh") || name.contains("Test")) {
           // Allow underscore in test-type method names