chore(gui): use step of 3600 for versions cleanup interval (#10317)

Currently, the input field has no step defined, meaning that it can be
increased with the arrow keys by the default value of "1". Considering
the fact that the default value is "3600" (seconds or one hour), it is
unlikely that the user wants to change it with such minimal steps.

For this reason, change the default step to "3600" (one hour). If the
user needs more granual control, they can still input the value
in seconds manually.

Signed-off-by: Tomasz Wilczyński <[email protected]>

Signed-off-by: Tomasz Wilczyński <[email protected]>

gui/default/syncthing/folder/editFolderModalView.html

@@ -146,7 +146,7 @@
           <div class="form-group" ng-if="internalVersioningEnabled()" ng-class="{'has-error': folderEditor.cleanupIntervalS.$invalid && folderEditor.cleanupIntervalS.$dirty}">
             <label translate for="cleanupIntervalS">Cleanup Interval</label>
             <div class="input-group">
-              <input name="cleanupIntervalS" id="cleanupIntervalS" class="form-control text-right" type="number" ng-model="currentFolder._guiVersioning.cleanupIntervalS" required="" min="0" max="31536000" aria-required="true" />
+              <input name="cleanupIntervalS" id="cleanupIntervalS" class="form-control text-right" type="number" ng-model="currentFolder._guiVersioning.cleanupIntervalS" required="" min="0" max="31536000" step="3600" aria-required="true" />
               <div class="input-group-addon" translate>seconds</div>
             </div>
             <p class="help-block">