Strip debug symbols from binaries

The debug symbols are only required for external tools (like debuggers or third party profilers). This does not affect Go stack traces or pprof.

Closes elastic#12768

CHANGELOG-developer.next.asciidoc

@@ -49,3 +49,4 @@ The list below covers the major changes between 7.0.0-rc2 and master only.
 - Add support to close beat.Client via beat.CloseRef (a subset of context.Context). {pull}13031[13031]
 - Add checks for types and formats used in fields definitions in `fields.yml` files. {pull}13188[13188]
 - Makefile included in generator copies files from beats repository using `git archive` instead of cp. {pull}13193[13193]
+- Strip debug symbols from binaries to reduce binary sizes. {issue}12768[12768]

dev-tools/mage/build.go

@@ -48,6 +48,9 @@ func DefaultBuildArgs() BuildArgs {
 	args := BuildArgs{
 		Name: BeatName,
 		CGO:  build.Default.CgoEnabled,
+		LDFlags: []string{
+			"-s", // Strip all debug symbols from binary (does not affect Go stack traces).
+		},
 		Vars: map[string]string{
 			"github.com/elastic/beats/libbeat/version.buildTime": "{{ date }}",
 			"github.com/elastic/beats/libbeat/version.commit":    "{{ commit }}",