Add index on chanid in iptv_channel and channelgroup (#991) #301

Job	Run time
Building MythTV on macOS 13 (Ventura) x86_64 using clang	8m 3s
Building MythTV on Ubuntu interim	7m 56s
Building MythTV on macOS 14 (Sonoma) arm64 using clang	3m 3s
Building MythTV on Ubuntu LTS	7m 42s
Building MythTV on Ubuntu devel	8m 5s
Building MythTV on Debian stable	7m 16s
Building MythTV on Fedora	8m 17s
Building MythTV on Fedora - Qt6	7m 24s
Building MythTV on Fedora - clang	7m 49s
Building MythTV on Fedora - CMake	10m 26s
	1h 16m 1s

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