clean-up "nolint" comments, remove unused ones

- fix "nolint" comments to be in the correct format (`//nolint:<linters>[,<linter>`
  no leading space, required colon (`:`) and linters.
- remove "nolint" comments for errcheck, which is disabled in our config.
- remove "nolint" comments that were no longer needed (nolintlint).
- where known, add a comment describing why a "nolint" was applied.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

pkg/cri/server/service.go

@@ -113,7 +113,7 @@ type criService struct {
 	baseOCISpecs map[string]*oci.Spec
 	// allCaps is the list of the capabilities.
 	// When nil, parsed from CapEff of /proc/self/status.
-	allCaps []string // nolint
+	allCaps []string //nolint:unused // Ignore on non-Linux
 	// unpackDuplicationSuppressor is used to make sure that there is only
 	// one in-flight fetch request or unpack handler for a given descriptor's
 	// or chain ID.