vet: add check for trailing spaces (#7576)

* vet: trailing spaces check

scripts/vet.sh

@@ -67,6 +67,9 @@ not git grep "\"github.com/golang/protobuf/*" -- "*.go" ':(exclude)reflection/te
 # - Ensure all usages of grpc_testing package are renamed when importing.
 not git grep "\(import \|^\s*\)\"google.golang.org/grpc/interop/grpc_testing" -- "*.go"
 
+# - Ensure that no trailing spaces are found.
+not git grep '[[:blank:]]$'
+
 # - Ensure all xds proto imports are renamed to *pb or *grpc.
 git grep '"github.com/envoyproxy/go-control-plane/envoy' -- '*.go' ':(exclude)*.pb.go' | not grep -v 'pb "\|grpc "'
 

security/advancedtls/examples/credential_reloading_from_files/README.md

@@ -9,7 +9,9 @@ Once the credential data needs to be updated, users just change the credential d
 
 A couple of things to note:
  1. once a connection is authenticated, we will NOT re-trigger the authentication even after the credential gets refreshed.
- 2. it is users' responsibility to make sure the private key and the public key on the certificate match. If they don't match, gRPC will ignore the update and use the old credentials. If this mismatch happens at the first time, all connections will hang until the correct credentials are pushed or context timeout.  
+ 2. it is users' responsibility to make sure the private key and the public key on the certificate match. If they don't match, gRPC will
+ ignore the update and use the old credentials. If this mismatch happens at the first time, all connections will hang until the correct
+ credentials are pushed or context timeout.
 
 ## Try it
 In directory `security/advancedtls/examples`:

security/advancedtls/testdata/server_cert_2.txt

@@ -88,4 +88,3 @@ Certificate:
          1d:b5:cc:6f:14:21:c4:89:07:9b:81:1d:9a:79:ff:bf:fd:ce:
          e4:77:11:0f:47:21:dc:d9:79:f3:40:26:56:5c:b4:86:32:8e:
          28:b9:14:e7:b3:fe:86:47
-