Fix memize option key typo

[ellatrix]

Description

I don't know why I thought the option was size instead of maxSize... This is problematic because we're keeping rich text value cache for every change in value, which is unlikely to be ever used again.

How has this been tested?

Screenshots

Types of changes

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.

[ellatrix]

Saw some intermittent e2e test failures.

Summary of all failing tests
FAIL specs/block-hierarchy-navigation.test.js (9.779s)
  ● Navigating the block hierarchy › should navigate block hierarchy using only the keyboard
    expect(value).toMatchSnapshot()
    Received value does not match stored snapshot "Navigating the block hierarchy should navigate block hierarchy using only the keyboard 1".
    - Snapshot
    + Received
    @@ -9,9 +9,13 @@
      <div class="wp-block-column"></div>
      <!-- /wp:column -->
      
      <!-- wp:column -->
      <div class="wp-block-column"><!-- wp:paragraph -->
    - <p>Third column</p>
    + <p></p>
      <!-- /wp:paragraph --></div>
      <!-- /wp:column --></div>
    - <!-- /wp:columns -->"
    + <!-- /wp:columns -->
    + 
    + <!-- wp:image -->
    + <figure class="wp-block-image"><img alt=""/></figure>
    + <!-- /wp:image -->"
      80 | 		await page.keyboard.type( 'Third column' );
      81 | 
    > 82 | 		expect( await getEditedPostContent() ).toMatchSnapshot();
         | 		                                       ^
      83 | 	} );
      84 | 
      85 | 	it( 'should appear and function even without nested blocks', async () => {
      at Object.toMatchSnapshot (specs/block-hierarchy-navigation.test.js:82:42)
      at tryCatch (../../node_modules/regenerator-runtime/runtime.js:62:40)
      at Generator.invoke [as _invoke] (../../node_modules/regenerator-runtime/runtime.js:288:22)
      at Generator.prototype.(anonymous function) [as next] (../../node_modules/regenerator-runtime/runtime.js:114:21)
      at asyncGeneratorStep (specs/block-hierarchy-navigation.test.js:9:103)
      at _next (specs/block-hierarchy-navigation.test.js:11:194)
Snapshot Summary
 › 1 snapshot failed from 1 test suite. Inspect your code changes or run `npm run test-e2e -- -u` to update them.
Test Suites: 1 failed, 34 passed, 35 total
Tests:       1 failed, 132 passed, 133 total
Snapshots:   1 failed, 62 passed, 63 total
Time:        289.871s

[aduth]

Saw some intermittent e2e test failures.

Yeah, I got one of those as well today. I'd seen this one off-and-on for quite a long time now, but not as much recently.