[template] Fix "rule alink_thin" in the //build/build_linux.ninja.template

*.a files in the $out can not be removed because they are static library needed by the building step.
From the view of gn, `gn clean` is only standard way to clean up everything about output.

Change-Id: I30c17cb33db2f3cdc6eebd612d5aa474920cb15d
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/17180
Commit-Queue: David Turner <digit@google.com>
Reviewed-by: Takuto Ikuta <tikuta@google.com>
Reviewed-by: David Turner <digit@google.com>

build/build_linux.ninja.template

diff --git a/build/build_linux.ninja.template b/build/build_linux.ninja.template
index ab117fb..27339a7 100644
--- a/build/build_linux.ninja.template
+++ b/build/build_linux.ninja.template
@@ -5,7 +5,7 @@
   deps = gcc
 
 rule alink_thin
-  command = rm -f $out && $ar rcsT $out $in
+  command = $ar rcsT $out $in
   description = AR $out
 
 rule link