Drop "v" from the version tag, add tilde back

When -Dversion-tag was initially added in edaa157918,
I used "v" without any comment. But upstream does not use "v", so we have
versions which don't compare directly:

$ build/systemctl --version|head -n1
systemd 251 (251-66-g7e46a5c+)
$ systemctl --version|head -n1
systemd 251 (v251-1.fc37)

And in 3c4f9413a7, when -Dshared-lib-tag= was
introduced, %{version} was replaced by %{version_no_tilde}, again without any
specific comment. For the shared-lib-tag, it makes sense to use _no_tilde,
because it's enough to have non-conflicting file names, and we don't compare
the tags. I guess I wanted both uses to be consistent. But if we substitute
the tilde, we can't do proper comparisons.

I noticed the following issue: with sd-boot installed from git and a
package, upgrades wouldn't work:

Comparing versions: "systemd-boot v251-1.fc37" < "systemd-boot 251-rc1-390-g3603f15
Skipping "/boot/efi/EFI/systemd/systemd-bootx64.efi", since newer boot loader version in place already.

The two changes should make those comparisons work properly in most
cases.

systemd.spec

@@ -526,7 +526,7 @@ CONFIGURE_OPTS=(
         -Db_lto=%[%{with lto}?"true":"false"]
         -Db_ndebug=false
         -Dman=true
-        -Dversion-tag=v%{version_no_tilde}-%{release}
+        -Dversion-tag=%{version}-%{release}
         # https://bugzilla.redhat.com/show_bug.cgi?id=1906010
         # -Dshared-lib-tag=%{version_no_tilde}-%{release}
         -Dfallback-hostname=%[0%{?fedora}?"fedora":"localhost"]
@@ -1020,6 +1020,7 @@ fi
 %changelog
 * Wed May 25 2022 Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> - 251.1-2
 - Supress errors from useradd/groupadd (#2090129)
+- Drop "v" from the version tag, add tilde back
 
 * Tue May 24 2022 Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> - 251.1-1
 - First bugfix release for 250