Reland "Enable sync trusted vault support by default"

This reverts commit 00eeaa2c.

Reason for revert: was temporarily disabled for branch point.

Original change's description:
> Revert "Reland "Enable sync trusted vault support by default""
> 
> This reverts commit be06dabb.
> 
> Reason for revert: the feature is not ready yet.
> 
> Original change's description:
> > Reland "Enable sync trusted vault support by default"
> > 
> > This is a reland of f52179a5
> > 
> > The feature was disabled by default before branching because some
> > implementation parts were missing on Android.
> > 
> > Original change's description:
> > > Enable sync trusted vault support by default
> > >
> > > The feature is in a working state can be enabled by default.
> > >
> > > Bug: 1000146
> > > Change-Id: I66ef6f65d97234f47eaa76d1daafb8d3637692ed
> > > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2000702
> > > Reviewed-by: Marc Treib <treib@chromium.org>
> > > Commit-Queue: Mikel Astiz <mastiz@chromium.org>
> > > Cr-Commit-Position: refs/heads/master@{#731898}
> > 
> > Bug: 1000146
> > Change-Id: If2c11c87bbc021daaa6656f9e85b592302dd8327
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2035966
> > Reviewed-by: Marc Treib <treib@chromium.org>
> > Commit-Queue: Mikel Astiz <mastiz@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#738548}
> 
> TBR=treib@chromium.org,mastiz@chromium.org
> 
> # Not skipping CQ checks because original CL landed > 1 day ago.
> 
> Bug: 1000146
> Change-Id: I44607cf1822145fb8a98e4a72a1361dbae274b00
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2127091
> Commit-Queue: Mikel Astiz <mastiz@chromium.org>
> Reviewed-by: Mikel Astiz <mastiz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#755994}

TBR=treib@chromium.org,mastiz@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1000146
Change-Id: I749d1b18772534611cf218d08f61587ec2a30b3a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2134020Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756638}

components/sync/engine/sync_engine_switches.cc

@@ -26,7 +26,7 @@ const base::Feature kSyncUseScryptForNewCustomPassphrases{
     "SyncUseScryptForNewCustomPassphrases", base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kSyncSupportTrustedVaultPassphrase{
-    "SyncSupportTrustedVaultPassphrase", base::FEATURE_DISABLED_BY_DEFAULT};
+    "SyncSupportTrustedVaultPassphrase", base::FEATURE_ENABLED_BY_DEFAULT};
 
 // If enabled sync cycle ends by collecting contributions from all datatypes
 // and having less than max_commit_batch_size() entries to commit. If disabled