Print Preview: Fix some element widths

Update some element widths, to prevent them from being cut off after
the changes in https://crrev.com/c/1585326. Specifically fixing:
- Advanced settings paper-button
- Error messages for scaling/copies sections

Bug: 959691,959694
Change-Id: I324e188f1c05e4a7c5261c60fa58f6441eb1df5f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1597966Reviewed-by: Hector Carmona <hcarmona@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#657323}

chrome/browser/resources/print_preview/ui/advanced_options_settings.html

@@ -11,13 +11,9 @@
   <template>
     <style include="print-preview-shared paper-button-style">
       paper-button {
-        --button-margin: 2px;
-        height: unset;
-        margin: var(--button-margin);
-        margin-inline-start: 0;
         min-height: 32px;
         text-align: center;
-        width: calc(100% - var(--button-margin) - 15px);
+        width: calc(100% - 2 * var(--print-preview-sidebar-margin));
       }
     </style>
     <print-preview-settings-section>

chrome/browser/resources/print_preview/ui/number_settings_section.html

@@ -27,7 +27,6 @@
       .input-wrapper {
         align-items: center;
         display: flex;
-        width: 100%;
       }
 
       :host([input-valid]) cr-input {