Remove various unused flag metadata.

They do not have any references in the codebase. The flags are:

autofill-reject-company-birthyear
cct-target-translate-language
enable-webrtc-new-encode-cpu-load-estimator
improved-cookie-controls
passive-mixed-content-warning

Change-Id: I91022655d4659ce3cfec88308fc79156b894624d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2415551Reviewed-by: Christian Dullweber <dullweber@chromium.org>
Reviewed-by: Parastoo Geranmayeh <parastoog@google.com>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Commit-Queue: Parastoo Geranmayeh <parastoog@google.com>
Cr-Commit-Position: refs/heads/master@{#808961}

chrome/browser/flag-metadata.json

@@ -356,11 +356,6 @@
     "owners": [ "ftirelo", "tmartino" ],
     "expiry_milestone": 78
   },
-  {
-    "name": "autofill-reject-company-birthyear",
-    "owners": [ "parastoog" ],
-    "expiry_milestone": 79
-  },
   {
     "name": "autofill-restrict-formless-form-extraction",
     "owners": [ "rogerm" ],
@@ -461,11 +456,6 @@
     "owners": [ "rhalavati", "//chrome/android/java/src/org/chromium/chrome/browser/customtabs/OWNERS" ],
     "expiry_milestone": 88
   },
-  {
-    "name": "cct-target-translate-language",
-    "owners": [ "amalova" ],
-    "expiry_milestone": 76
-  },
   {
     "name": "cdm-factory-daemon",
     "owners": [ "jkardatzke", "xhwang", "chromeos-gfx-video@google.com" ],
@@ -2362,11 +2352,6 @@
     "owners": [ "alessiob" ],
     "expiry_milestone": 103
   },
-  {
-    "name": "enable-webrtc-new-encode-cpu-load-estimator",
-    "owners": [ "nisse" ],
-    "expiry_milestone": 85
-  },
   {
     "name": "enable-webrtc-pipewire-capturer",
     "owners": [ "tomas.popela@gmail.com" ],
@@ -2824,11 +2809,6 @@
     "owners": [ "mcharland", "tmartino" ],
     "expiry_milestone": 88
   },
-  {
-    "name": "improved-cookie-controls",
-    "owners": [ "dullweber", "huanzhong" ],
-    "expiry_milestone": 86
-  },
   {
     "name": "impulse-scroll-animations",
     "owners": [ "dlibby@microsoft.com", "sarsha@microsoft.com" ],
@@ -3636,11 +3616,6 @@
     "owners": [ "nzolghadr", "input-dev" ],
     "expiry_milestone": 78
   },
-  {
-    "name": "passive-mixed-content-warning",
-    "owners": [ "carlosil", "estark" ],
-    "expiry_milestone": 83
-  },
   {
     "name": "password-change-in-settings",
     "owners": [ "kolos" ],