Remove binding="strong" in default 70-noto-cjk.conf
If we keep the binding="strong", then fontconfig will ignore fallback order in user level. Therefore, Noto Sans will be always the default font in specific language.
```[8]
<match target="pattern">
<test name="lang">
<string>zh-cn</string>
</test>
<test name="family">
<string>serif</string>
</test>
<edit name="family" mode="prepend" binding="strong">
<string>Noto Serif CJK SC</string>
</edit>
</match>
```
Reproduce steps:
1. Use firefox which respect the fontconfig setting
2. Try to use below replace rule in user level ~/.config/fontconfig/fonts.conf
```
<match target="pattern">
<test name="family" compare="contains">
<string>Noto Sans CJK</string>
</test>
<edit name="family" mode="prepend" binding="strong">
<string>THE FONT YOU WANT</string>
</edit>
</match>
```
3. Refresh the font cache: fc-cache -fv
4. open a page which contains CJK, such as Arch wiki
5. Then press F12 to check the font
issue