(core) Update text in the delete-page dialog

Summary:
In the delete-page dialog, for the option to keep the data, use the somewhat
clearer text "Keep data and delete page".

Test Plan: No changes to testId, should not affect tests.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D3612

app/client/ui/Pages.ts

@@ -136,7 +136,7 @@ function buildPrompt(tableNames: string[], onSave: (option: RemoveOption) => Pro
           buildOption(selected, 'data', `Delete data and this page.`),
           buildOption(selected, 'page',
             [
-              `Delete this page, but do not delete data. `,
+              `Keep data and delete page. `,
               `Table will remain available in `,
               cssLink(urlState().setHref({docPage: 'data'}), 'raw data page', { target: '_blank'}),
               `.`