Merge bitcoin-core/gui#664: Prevent wrong handling of %2 token by Transifex

8ed2b72 qt: Prevent wrong handling of `%2` token by Transifex (Hennadii Stepanov)

Pull request description:

  On master (124e75a), Transifex translation check fails for https://github.com/bitcoin-core/gui/blob/124e75a41ea0f3f0e90b63b0c41813184ddce2ab/src/qt/forms/intro.ui#L206 with a message:
  > The expression '%2G' is not present in the translation.

  In "Organization Settings" --> ["Translation checks"](https://www.transifex.com/bitcoin/settings/validations/) I have changed the status of the "**Variable substitution specifiers (like "%s") are preserved in the translations.**" check from "error" to "warning" temporarily. This setting should be reverted after applying this PR change.

  [Noted](https://www.transifex.com/bitcoin/bitcoin/translate/#ru/qt-translation-024x/436102928/) by Transifex user [AHOHNMYC](https://www.transifex.com/user/profile/AHOHNMYC/).

  I faced the same issue while working on Ukrainian translation.

ACKs for top commit:
  katesalazar:
    ACK 8ed2b72
  jarolrod:
    ACK 8ed2b72

Tree-SHA512: 304f795ac9241ac8453c614ed18d967226d9d515f9ea079b51af5bcbe2f0760ca7dcaea5efb38207720cb7a18159c2bcd337b961bc522a128715c70e0db81061

Author: hebasto

src/qt/forms/intro.ui

@@ -203,7 +203,7 @@
    <item>
     <widget class="QLabel" name="lblExplanation1">
      <property name="text">
-      <string>When you click OK, %1 will begin to download and process the full %4 block chain (%2GB) starting with the earliest transactions in %3 when %4 initially launched.</string>
+      <string>When you click OK, %1 will begin to download and process the full %4 block chain (%2 GB) starting with the earliest transactions in %3 when %4 initially launched.</string>
      </property>
      <property name="wordWrap">
       <bool>true</bool>