Undefined string data variable gets recreated if the function that references it get re-analyzed

[xusheng6]

Repro steps:

1. Open the helloworld binary from https://github.com/Vector35/debugger/blob/dev/test/binaries/Darwin-arm64/helloworld
2. Navigate to 0x100003f90, undefine the data variable
3. Navigate to main function, re-analyze it
4. Observe the data variable gets recreated

This is not very surprising since the function analysis always create the string data variable when it sees fit. However, this is previously never noticed, probably because of https://github.com/Vector35/binaryninja-api/issues/5818