.gitlab/issue_templates: Move suggestions into comments

Many users forget to remove the suggestions from the bug template
when creating a new issue. So when searching for strings like "s390x"
or "Windows", you get a lot of unrelated issues in the results.
Thus let's move the suggestions into HTML comments - so they will
still show up in the markdown when editing the bug, while being
hidden/ignored in the final text or in the search queries.

Message-Id: <20221201133756.77216-1-thuth@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

.gitlab/issue_templates/bug.md

@@ -18,11 +18,11 @@ https://www.qemu.org/contribute/security-process/
 -->
 
 ## Host environment
- - Operating system: (Windows 10 21H1, Fedora 34, etc.)
- - OS/kernel version: (For POSIX hosts, use `uname -a`)
- - Architecture: (x86, ARM, s390x, etc.)
- - QEMU flavor: (qemu-system-x86_64, qemu-aarch64, qemu-img, etc.)
- - QEMU version: (e.g. `qemu-system-x86_64 --version`)
+ - Operating system:            <!-- Windows 10 21H1, Fedora 37, etc. -->
+ - OS/kernel version:           <!-- For POSIX hosts, use `uname -a` -->
+ - Architecture:                <!-- x86, ARM, s390x, etc. -->
+ - QEMU flavor:                 <!-- qemu-system-x86_64, qemu-aarch64, qemu-img, etc. -->
+ - QEMU version:                <!-- e.g. `qemu-system-x86_64 --version` -->
  - QEMU command line:
    <!--
    Give the smallest, complete command line that exhibits the problem.
@@ -35,9 +35,9 @@ https://www.qemu.org/contribute/security-process/
    ```
 
 ## Emulated/Virtualized environment
- - Operating system: (Windows 10 21H1, Fedora 34, etc.)
- - OS/kernel version: (For POSIX guests, use `uname -a`.)
- - Architecture: (x86, ARM, s390x, etc.)
+ - Operating system:            <!-- Windows 10 21H1, Fedora 37, etc. -->
+ - OS/kernel version:           <!-- For POSIX guests, use `uname -a`. -->
+ - Architecture:                <!-- x86, ARM, s390x, etc. -->
 
 
 ## Description of problem