GitHub+lint: reduce linter memory usage

To reduce the likelyhood of the linter OOMing on the GitHub runner, we
exclude any generated code from being inspected and also tune the golang
garbage collector to be a bit more agressive.

.github/workflows/main.yml

@@ -131,7 +131,7 @@ jobs:
           go-version: '${{ env.GO_VERSION }}'
 
       - name: lint
-        run: make lint
+        run: GOGC=50 make lint
 
   ########################
   # cross compilation

.golangci.yml

@@ -2,9 +2,11 @@ run:
   # timeout for analysis
   deadline: 10m
 
-  # Skip autogenerated files for mobile.
+  # Skip autogenerated files for mobile and gRPC.
   skip-files:
     - "mobile\\/.*generated\\.go"
+    - "\\.pb\\.go$"
+    - "\\.pb\\.gw\\.go$"
 
   skip-dirs:
     - channeldb/migration_01_to_11