The problem has been solved by
sudo dracut -f -o multipath
Thanks everyone for your help!
Here are some more details in case anyone else faces these problems.
I decided to run YaST to undo a change I mentioned above [Based on the document “Common problems and their solutions | Start-Up | openSUSE Leap 15.4” Section 21.2.1, I had gone to System > Boot Loader and made sure that “Write generic Boot Code to MBR” option was enabled.]
A yast text pop up box informed me “Unsupported Configuration” and “YaST cannot process current bootloader configuration.” I chose the option to Propose new configuration from scratch.
Then there were multiple messages that “PackageKit is blocking software management” which I had to deal with.
I restarted the system.
Then os-prober successfully found the Windows OS.
Then I ran
grub2-mkconfig -o /boot/grub2/grub.cfg
Then I restarted and was able to boot into Windows!
I can now boot into my new Leap 15.4 installation and my Windows installation. The one strange thing that happened only once after the second reboot was the following, which I ignored and simply tried again:
2233-HECI error during MEBx execution.
2206-End of POST HECI Failure.
Yesterday the opensuse forums system told me I had reached the limit for the number of posts for my first day, so I posted only 4 of the 7 parts of the output from lsinitrd. I think it is not necessary now, but if anyone wants to see the remaining 3 parts (or if they fixed susepaste) let me know.
Thanks again for your help!