Add the missing value to the SettingsPageInteractions enum in enums.xml

This enum must be kept in sync with the histogram of the same name in
resources/settings/metrics_browser_proxy.js, but it's currently not.

This causes a DCHECK when settings attempt to record this value.

Bug: None
Change-Id: If04dc1d3852854a02659d9bd056f10eafe80b8ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2025668Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Martin Šrámek <msramek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#736099}

tools/metrics/histograms/enums.xml

@@ -57935,6 +57935,7 @@ Called by update_net_trust_anchors.py.-->
   <int value="35" label="PRIVACY_SITE_SETTINGS_CLIPBOARD"/>
   <int value="36" label="PRIVACY_SITE_SETTINGS_PAYMENT_HANDLER"/>
   <int value="37" label="PRIVACY_SITE_SETTINGS_MIXEDSCRIPT"/>
+  <int value="38" label="PRIVACY_SITE_SETTINGS_BLUETOOTH_SCANNING"/>
 </enum>
 
 <enum name="SettingsResetPromptConfigError">