[NTP] Fix the line height for customize button.

Fix the line height to take exactly as much space as the specified
font. Otherwise, if it takes more space then vertical alignment doesn't
work as button doesn't have enough height.

Bug: 990956
Change-Id: I45746cc8cf6863acb58880b83fad3f41feba7abb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1761219Reviewed-by: Kristi Park <kristipark@chromium.org>
Commit-Queue: Gayane Petrosyan <gayane@chromium.org>
Cr-Commit-Position: refs/heads/master@{#688368}

chrome/browser/resources/local_ntp/customize.css

@@ -95,6 +95,7 @@ html[dir=rtl] #edit-bg {
   color: rgb(var(--GB600-rgb));
   display: none;
   font-size: 14px;
+  line-height: 1;
   padding-inline-end: 12px;
   padding-inline-start: 8px;
   user-select: none;