[DEPS] Add condition to exclude legacy src_internal

This condition allows us not to get old src_internal path at
/src-internal.

R=gbeaty@google.com

Bug: 1423117
Change-Id: Iaa9c4174980a58b9758cfdebda7fd7b3e8723c7d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4638354
Auto-Submit: Josip Sokcevic <sokcevic@chromium.org>
Reviewed-by: Garrett Beaty <gbeaty@google.com>
Commit-Queue: Josip Sokcevic <sokcevic@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1161576}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4643249
Cr-Commit-Position: refs/branch-heads/5845@{#106}
Cr-Branched-From: 5a5dff6-refs/heads/main@{#1160321}

DEPS

@@ -124,6 +124,10 @@ vars = {
   # custom_vars.
   'checkout_src_internal': False,
 
+  # Checkout legacy src_internal. This variable is ignored if
+  # checkout_src_internal is set as false.
+  'checkout_legacy_src_internal': True,
+
   # For super-internal deps. Set by the official builders.
   'checkout_google_internal': False,
 
@@ -2002,7 +2006,7 @@ deps = {
 
   'src-internal': {
     'url': Var('chrome_git') + '/chrome/src-internal.git' + '@' + Var('src_internal_revision'),
-    'condition': 'checkout_src_internal',
+    'condition': 'checkout_src_internal and checkout_legacy_src_internal',
   },
 
   'src/internal': {