move to golangci unused (#672)

Author: zirain

files/common/config/.golangci-format.yml

@@ -7,7 +7,7 @@
 
 service:
   # When updating this, also update the version stored in docker/build-tools/Dockerfile in the istio/tools repo.
-  golangci-lint-version: 1.38.x # use the fixed version to not introduce new linters unexpectedly
+  golangci-lint-version: 1.49.x # use the fixed version to not introduce new linters unexpectedly
 run:
   # timeout for analysis, e.g. 30s, 5m, default is 1m
   deadline: 20m

files/common/config/.golangci.yml

@@ -7,7 +7,7 @@
 
 service:
   # When updating this, also update the version stored in docker/build-tools/Dockerfile in the istio/tools repo.
-  golangci-lint-version: 1.38.x # use the fixed version to not introduce new linters unexpectedly
+  golangci-lint-version: 1.49.x # use the fixed version to not introduce new linters unexpectedly
 run:
   # timeout for analysis, e.g. 30s, 5m, default is 1m
   deadline: 20m
@@ -34,7 +34,6 @@ run:
 linters:
   disable-all: true
   enable:
-  - deadcode
   - errcheck
   - exportloopref
   - gocritic
@@ -47,12 +46,11 @@ linters:
   - lll
   - misspell
   - staticcheck
-  - structcheck
   - stylecheck
   - typecheck
   - unconvert
   - unparam
-  - varcheck
+  - unused
   - gci
   fast: false