minimal-bootstrap: trim gnugrep-static output

Disable NLS and remove installed documentation after keeping only the grep binary. The existing egrep and fgrep pruning remains in place.

Size impact against upstream/staging:

- gnugrep-static closure: 0.546 MiB -> 0.381 MiB (-0.165 MiB)

Assisted-by: codex with gpt-5.5-high

pkgs/os-specific/linux/minimal-bootstrap/gnugrep/static.nix

@@ -70,6 +70,7 @@ bash.runCommand "${pname}-${version}"
       --build=${buildPlatform.config} \
       --host=${hostPlatform.config} \
       --disable-dependency-tracking \
+      --disable-nls \
       CC=musl-gcc \
       CFLAGS=-static
 
@@ -79,4 +80,7 @@ bash.runCommand "${pname}-${version}"
     # Install
     make -j $NIX_BUILD_CORES install-strip
     rm $out/bin/{egrep,fgrep}
+
+    # Remove documentation not needed in the bootstrap chain.
+    rm -rf $out/share
   ''