Revert "[CrOS Cellular] Enable eSIM Policies flag by default"

This reverts commit 710787e.

Reason for revert: Causes DMServer failures; see b/222695409.

Original change's description:
> [CrOS Cellular] Enable eSIM Policies flag by default
>
> Change-Id: I8c0cc9a732c73c46f56f4c69755b5eb5c9c49fad
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3408313
> Auto-Submit: Kyle Horimoto <khorimoto@chromium.org>
> Reviewed-by: Jason Zhang <jiajunz@google.com>
> Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#963706}

(cherry picked from commit 2b072a8)

Bug: b/222748130
Change-Id: I5f5486b48ef94194d33d0a0f2b7530b786279a5d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3504090
Auto-Submit: Kyle Horimoto <khorimoto@chromium.org>
Reviewed-by: Jason Zhang <jiajunz@google.com>
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#977846}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3504491
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/branch-heads/4896@{#306}
Cr-Branched-From: 1f63ff4-refs/heads/main@{#972766}

ash/constants/ash_features.cc

@@ -568,7 +568,8 @@ const base::Feature kEolWarningNotifications{"EolWarningNotifications",
 
 // Enables or disables enterprise policy control for eSIM cellular networks.
 // See https://crbug.com/1231305.
-const base::Feature kESimPolicy{"ESimPolicy", base::FEATURE_ENABLED_BY_DEFAULT};
+const base::Feature kESimPolicy{"ESimPolicy",
+                                base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Enable or disable support for touchpad with haptic feedback.
 const base::Feature kExoHapticFeedbackSupport("ExoHapticFeedbackSupport",