[repo] Remove Jan from default reviewer assignment (#35441)

cc @jtattermusch

.github/CODEOWNERS

@@ -2,12 +2,12 @@
 # Uses OWNERS files in different modules throughout the
 # repository as the source of truth for module ownership.
 /**/OWNERS @markdroth @a11r
-/bazel/** @jtattermusch @veblush @gnossen
-/cmake/** @jtattermusch @apolcyn
+/bazel/** @veblush @gnossen
+/cmake/** @veblush @apolcyn
 /src/core/ext/filters/client_channel/** @markdroth
 /src/core/ext/transport/chttp2/transport/** @ctiller
 /src/core/ext/xds/** @markdroth
 /src/core/lib/resolver/** @markdroth
 /src/core/lib/service_config/** @markdroth
-/tools/dockerfile/** @jtattermusch @apolcyn
+/tools/dockerfile/** @drfloob @apolcyn @gnossen
 /tools/run_tests/xds_k8s_test_driver/** @sergiitk @XuanWang-Amos @gnossen

.github/ISSUE_TEMPLATE/bug_report_csharp.md

@@ -2,7 +2,7 @@
 name: Report a gRPC C# bug
 about: Create a report to help us improve
 labels: kind/bug, priority/P2, lang/C#
-assignees: jtattermusch
+assignees: apolcyn
 
 ---
 

.github/ISSUE_TEMPLATE/feature_request_csharp.md

@@ -2,7 +2,7 @@
 name: Request a gRPC C# feature
 about: Suggest an idea for this project
 labels: kind/enhancement, priority/P2, lang/C#
-assignees: jtattermusch
+assignees: apolcyn
 
 ---