Length of path and pathlowercase in symbols schema is confusing

Created by: blanet

Actually this is not a BUG because sqlite doesn't care about the VARCHAR length when storing data as far as I know.

But the length for path and pathlowercase do need to be equal because they are just used in case-sensitive related cases.

https://github.com/sourcegraph/sourcegraph/blob/21017ff137684ce359f248c710f2ba7a5cc8b582/cmd/symbols/internal/symbols/search.go#L310-L323