be less strict when figuring out major version in initrd

We only care for the major part of the version, so it's sufficient to
grep without the dot, which is not present on CentOS initrd.

CentOS Stream 8:

    VERSION="8 dracut-049-224.git20230330.el8"
    VERSION_ID=049-224.git20230330.el8

CentOS Stream 9:

    VERSION="9 dracut-057-38.git20230725.el9"
    VERSION_ID="9"

RHEL 8.8:

    VERSION="8.8 (Ootpa) dracut-049-223.git20230119.el8"
    VERSION_ID=049-223.git20230119.el8

RHEL 9.2:

    VERSION="9.2 (Plow) dracut-057-21.git20230214.el9"
    VERSION_ID="9.2"

Ideally, we would just use the major part of VERSION_ID, but this is set
to the underlying OS'es VERSION_ID only since dracut 050 [1] and EL8
ships with 049.

[1] dracutdevs/dracut@72ae1c4

repos/system_upgrade/common/actors/commonleappdracutmodules/files/dracut/85sys-upgrade-redhat/do-upgrade.sh

@@ -9,7 +9,7 @@ type getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
 
 get_rhel_major_release() {
     local os_version
-    os_version=$(grep -o '^VERSION="[0-9][0-9]*\.' /etc/initrd-release | grep -o '[0-9]*')
+    os_version=$(grep -o '^VERSION="[0-9][0-9]*' /etc/initrd-release | grep -o '[0-9]*')
     [ -z "$os_version" ] && {
         # This should not happen as /etc/initrd-release is supposed to have API
         # stability, but check is better than broken system.

repos/system_upgrade/common/actors/commonleappdracutmodules/files/dracut/90sys-upgrade/initrd-system-upgrade-generator

@@ -1,7 +1,7 @@
 #!/bin/sh
 
 get_rhel_major_release() {
-    _os_version=$(cat /etc/initrd-release | grep -o '^VERSION="[0-9][0-9]*\.' | grep -o '[0-9]*')
+    _os_version=$(cat /etc/initrd-release | grep -o '^VERSION="[0-9][0-9]*' | grep -o '[0-9]*')
     [ -z "$_os_version" ] && {
         # This should not happen as /etc/initrd-release is supposed to have API
         # stability, but check is better than broken system.