Impedance control in board setup is not set

Description

The "Impedance Control" option can be set via the "Board Setup" dialog but is not saved.

Steps to reproduce

1. Open PCB Editor
2. Open "Board Setup->Physical Stackup".
3. Tick "Impedance Control".
4. Set all related Epsilon and Loss Tan values.
5. Click OK.
6. Check the "Impedance Control" again, and it is not ticked.
7. Place "Board Characteristics", the "Impedance Control" is "No".
8. Open the PCB file in text editor, the "Impedance Control" field is "no" but it can be set to "yes" to take the effect.

KiCad Version

Application: KiCad x86_64 on x86_64

Version: 7.0.7-rc1-202308111703~c4914a64bb~ubuntu23.04.1, release build

Libraries:
	wxWidgets 3.2.2
	FreeType 2.12.1
	HarfBuzz 6.0.0
	FontConfig 2.14.1
	libcurl/7.88.1 OpenSSL/3.0.8 zlib/1.2.13 brotli/1.0.9 zstd/1.5.4 libidn2/2.3.3 libpsl/0.21.2 (+libidn2/2.3.3) libssh/0.10.4/openssl/zlib nghttp2/1.52.0 librtmp/2.3

Platform: Ubuntu 23.04, 64 bit, Little endian, wxGTK, KDE, wayland

Build Info:
	Date: Aug 11 2023 17:03:18
	wxWidgets: 3.2.2 (wchar_t,wx containers) GTK+ 3.24
	Boost: 1.74.0
	OCC: 7.6.3
	Curl: 7.88.1
	ngspice: 38
	Compiler: GCC 12.3.0 with C++ ABI 1017

Build settings:
	KICAD_SPICE=ON