Residual configuration of grub-pc not removed during Ubuntu 25.04 installation

[Cristiano Fraga G. Nunes]

During the installation of Ubuntu 25.04 on a UEFI system, the installer correctly installs the grub-efi-amd64 package. However, the residual configuration files for the grub-pc package are left on the system.

If the user runs the command:
sudo apt remove grub-pc --purge

after installation, this results in the removal of the GRUB bootloader, leading to a non-bootable system.

**Steps to Reproduce:**

1. Install Ubuntu 25.04 on a UEFI system.
2. Complete the installation and boot into the system.
3. Run dpkg -l | grep grub and observe that both grub-pc (residual config) and grub-efi-amd64 are listed.
4. Run sudo apt remove grub-pc --purge.
5. Reboot the system - the bootloader is missing, and the system fails to boot.

**Expected Behavior:**

The installer should completely remove grub-pc and its configuration during installation on UEFI systems.

Alternatively, purging grub-pc post-install should not interfere with the functioning of grub-efi-amd64.

**Actual Behavior:**

Residual grub-pc configuration remains.

Purging it removes or interferes with the EFI GRUB setup.

The system becomes unbootable after reboot.

ProblemType: Bug
DistroRelease: Ubuntu 25.04
Package: grub2 (not installed)
ProcVersionSignature: Ubuntu 6.14.0-15.15-generic 6.14.0
Uname: Linux 6.14.0-15-generic x86_64
ApportVersion: 2.32.0-0ubuntu3
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Thu Apr 10 14:27:38 2025
InstallationDate: Installed on 2025-04-04 (6 days ago)
InstallationMedia: Ubuntu 25.04 "Plucky Puffin" - Beta amd64 (20250326.6)
ProcEnviron:
 LANG=en_US.UTF-8
 PATH=(custom, no user)
 SHELL=/bin/bash
 TERM=xterm-256color
 XDG_RUNTIME_DIR=<set>
SourcePackage: grub2
UpgradeStatus: No upgrade log present (probably fresh install)