Disable errorprone RequestExplicitNullMarking

Currently not causing failures, but spamming warnings.

Ported from open-telemetry/opentelemetry-java#7890

Author: trask

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

@@ -124,6 +124,7 @@ tasks {
 
         // Requires adding compile dependency to JSpecify
         disable("AddNullMarkedToPackageInfo")
+        disable("RequireExplicitNullMarking")
 
         if (testLatestDeps) {
           // Some latest dep tests are compiled for java 17 although the base version uses an older