[otelcol] Fix grpclogger to capture correct caller location (#10773)

#### Description
Cleaned up Grpc logs to make them reference the location where the log
statements are written instead of zapgrpc/zapgrpc.go:176

#### Link to tracking issue
Fixes #10772
Fixes jaegertracing/jaeger#5784

---------

Signed-off-by: Yuri Shkuro <github@ysh.us>
Co-authored-by: Yuri Shkuro <github@ysh.us>
Co-authored-by: Yuri Shkuro <yurishkuro@users.noreply.github.com>

otelcol/internal/grpclog/logger.go

@@ -27,7 +27,7 @@ func SetLogger(baseLogger *zap.Logger, loglevel zapcore.Level) *zapgrpc.Logger {
 			c = core
 		}
 		return c.With([]zapcore.Field{zap.Bool("grpc_log", true)})
-	})))
+	}), zap.AddCallerSkip(5)))
 
 	grpclog.SetLoggerV2(logger)
 	return logger

otelcol/internal/grpclog/logger_test.go

@@ -9,6 +9,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
+	"google.golang.org/grpc/grpclog"
 )
 
 func TestGRPCLogger(t *testing.T) {
@@ -50,29 +51,45 @@ func TestGRPCLogger(t *testing.T) {
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
 			obsInfo, obsWarn := false, false
+			callerInfo := ""
 			hook := zap.Hooks(func(entry zapcore.Entry) error {
 				switch entry.Level {
 				case zapcore.InfoLevel:
 					obsInfo = true
 				case zapcore.WarnLevel:
 					obsWarn = true
 				}
+				callerInfo = entry.Caller.String()
 				return nil
 			})
 
 			// create new collector zap logger
 			logger, err := test.cfg.Build(hook)
 			assert.NoError(t, err)
 
-			// create colGRPCLogger
+			// create GRPCLogger
 			glogger := SetLogger(logger, test.cfg.Level.Level())
 			assert.NotNil(t, glogger)
-
-			glogger.Info(test.name)
-			glogger.Warning(test.name)
-
+			// grpc does not usually call the logger directly, but through various wrappers that add extra depth
+			component := &mockComponent{logger: grpclog.Component("channelz")}
+			component.Info(test.name)
+			component.Warning(test.name)
 			assert.Equal(t, obsInfo, test.infoLogged)
 			assert.Equal(t, obsWarn, test.warnLogged)
+			// match the file name and line number of Warning() call above
+			assert.Contains(t, callerInfo, "internal/grpclog/logger_test.go:76")
 		})
 	}
 }
+
+type mockComponent struct {
+	logger grpclog.DepthLoggerV2
+}
+
+func (c *mockComponent) Info(args ...any) {
+	c.logger.Info(args...)
+}
+
+func (c *mockComponent) Warning(args ...any) {
+	c.logger.Warning(args...)
+}