Update learn more string of FooterPrefernce

Replace FooterPreference#SetLearnMoreContentDescription() with
FooterPreference#SetLearnMoreText().

This is a requirement: All links, controls, and buttons should
also have comprehensible text or tooltip text, so users can identify its
purpose, independent of context, such as when using the URL list from
TalkBack’s local context menu.

Bug: 215045903
Test: manual & robotest
Change-Id: Ib657ba336c5688c1434a58611dea3891001afe14

src/com/android/settings/fuelgauge/AdvancedPowerUsageDetail.java

@@ -19,8 +19,8 @@ package com.android.settings.fuelgauge;
 import android.annotation.UserIdInt;
 import android.app.Activity;
 import android.app.ActivityManager;
-import android.app.settings.SettingsEnums;
 import android.app.backup.BackupManager;
+import android.app.settings.SettingsEnums;
 import android.content.Context;
 import android.content.Intent;
 import android.content.pm.PackageManager;
@@ -386,7 +386,7 @@ public class AdvancedPowerUsageDetail extends DashboardFragment implements
         if (helpIntent != null) {
             mFooterPreference.setLearnMoreAction(v ->
                     startActivityForResult(helpIntent, /*requestCode=*/ 0));
-            mFooterPreference.setLearnMoreContentDescription(
+            mFooterPreference.setLearnMoreText(
                     context.getString(R.string.manager_battery_usage_link_a11y));
         }
     }

src/com/android/settings/fuelgauge/batterysaver/BatterySaverSettings.java

@@ -90,7 +90,7 @@ public class BatterySaverSettings extends DashboardFragment {
                         getString(R.string.help_url_battery_saver_settings),
                         /*backupContext=*/ ""), /*requestCode=*/ 0);
             });
-            pref.setLearnMoreContentDescription(getString(R.string.battery_saver_link_a11y));
+            pref.setLearnMoreText(getString(R.string.battery_saver_link_a11y));
         }
     }
 }