[web] Remove invalid prop marginSize

Summary:
This prop isn't recognized by React and removing it doesn't have any visual impact.

https://linear.app/comm/issue/ENG-10096/remove-invalid-marginsize-property-from-the-qr-code-screen-on-web

Test Plan: Open the QR screen and check if it looks the same after this change. Also check the console to see if the warning disappeared.

Reviewers: kamil, bartek

Reviewed By: kamil

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D14266

web/account/log-in-form.react.js

@@ -176,7 +176,7 @@ function LoginForm() {
         </div>
         <div className={css.qrCodeContainer}>
           <div className={css.qrCodeWrapper}>
-            <QRCodeSVG value={qrCodeURL} size={195} marginSize={4} level="L" />
+            <QRCodeSVG value={qrCodeURL} size={195} level="L" />
           </div>
         </div>
         <div className={css.modal_text}>

web/account/qr-code-login.react.js

@@ -37,7 +37,7 @@ function QRCodeLogin(): React.Node {
         Open the Comm app on your phone and scan the QR code below
       </div>
       <div className={css.qrCodeContainer}>
-        <QRCodeSVG value={qrCodeURL} size={300} marginSize={4} level="L" />
+        <QRCodeSVG value={qrCodeURL} size={300} level="L" />
       </div>
       <div className={css.instructionsContainer}>
         <div className={css.instructionsTitle}>How to find the scanner:</div>