pkg/util/allstacks: wrap the stack traces with debugutil.SafeStack

The functions Get() and GetWithBuf() internally call runtime.Stack() to
fetch the calling go routine's stack trace.

This commit changes the return type of both the function from []byte to
debugutil.SafeStack (introduced in #136288). This will ensure that the
stack traces generated using these function are not redacted.

Part of: CRDB-15292
Epic: CRDB-37533
Release note: None

pkg/util/allstacks/BUILD.bazel

@@ -5,4 +5,5 @@ go_library(
     srcs = ["allstacks.go"],
     importpath = "github.com/cockroachdb/cockroach/pkg/util/allstacks",
     visibility = ["//visibility:public"],
+    deps = ["//pkg/util/debugutil"],
 )

pkg/util/allstacks/allstacks.go

@@ -5,18 +5,22 @@
 
 package allstacks
 
-import "runtime"
+import (
+	"runtime"
+
+	"github.com/cockroachdb/cockroach/pkg/util/debugutil"
+)
 
 // Get returns all stacks, except if that takes more than 512mb of memory, in
 // which case it returns only 512mb worth of stacks (clipping the last stack
 // if necessary).
-func Get() []byte {
+func Get() debugutil.SafeStack {
 	return GetWithBuf(nil)
 }
 
 // GetWithBuf is like Get, but tries to use the provided slice first, allocating
 // a new, larger, slice only if necessary.
-func GetWithBuf(buf []byte) []byte {
+func GetWithBuf(buf []byte) debugutil.SafeStack {
 	buf = buf[:cap(buf)]
 	// We don't know how big the traces are, so grow a few times if they don't
 	// fit. Start large, though.

pkg/util/debugutil/debugutil.go

@@ -45,6 +45,9 @@ func init() {
 	}(os.Getppid()))
 }
 
+// SafeStack is an alias for []byte that handles redaction. Use this type
+// instead of []byte when you are sure that the stack trace does not contain
+// sensitive information.
 type SafeStack []byte
 
 func (s SafeStack) SafeValue() {}