[chore] Update codeowners for groupbyattrsprocessor (open-telemetry#23414)

Updating CODEOWNERS for processor/groupbyattrsprocessor

Author: rnishtala-sumo

.github/CODEOWNERS

@@ -137,7 +137,7 @@ processor/cumulativetodeltaprocessor/                    @open-telemetry/collect
 processor/datadogprocessor/                              @open-telemetry/collector-contrib-approvers @mx-psi @gbbr @dineshg13
 processor/deltatorateprocessor/                          @open-telemetry/collector-contrib-approvers @Aneurysm9
 processor/filterprocessor/                               @open-telemetry/collector-contrib-approvers @TylerHelmuth @boostchicken
-processor/groupbyattrsprocessor/                         @open-telemetry/collector-contrib-approvers
+processor/groupbyattrsprocessor/                         @open-telemetry/collector-contrib-approvers @rnishtala-sumo
 processor/groupbytraceprocessor/                         @open-telemetry/collector-contrib-approvers @jpkrohling
 processor/k8sattributesprocessor/                        @open-telemetry/collector-contrib-approvers @dmitryax @rmfitzpatrick @fatsheep9146
 processor/logstransformprocessor/                        @open-telemetry/collector-contrib-approvers @djaglowski @dehaansa