Fix brace expansion in AIC8800 bluetooth service check across board configs

## Problem

The `post_family_tweaks__enable_aic8800_bluetooth_service()` function in several board configuration files uses brace expansion with `test -f`, which causes the test command to fail because it receives multiple arguments instead of one.

## Affected Files

- `config/boards/kickpik2b.csc`
- `config/boards/radxa-cubie-a5e.csc`
- `config/boards/radxa-zero3.csc`

## Current Problematic Code

```bash
if chroot_sdcard test -f {/lib/,/usr/lib/,/etc/}systemd/system/aic-bluetooth.service; then
```

## Solution

Replace with explicit OR checks:

```bash
if chroot_sdcard test -f /lib/systemd/system/aic-bluetooth.service || \
chroot_sdcard test -f /usr/lib/systemd/system/aic-bluetooth.service || \
chroot_sdcard test -f /etc/systemd/system/aic-bluetooth.service; then
```

## Context

This issue was identified during review of PR #8511 but deferred to a separate PR to keep changes focused.

**References:**
- PR: https://github.com/armbian/build/pull/8511
- Comment: https://github.com/armbian/build/pull/8511#discussion_r2301112753

**Requested by:** @leggewie