[clang] [clang] increase default constexpr step limit (PR #143785)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

Typically we set limits like this for at least somewhat of a reasoned-reason.  Can we do some archeology to figure out when/why we decided on this limit?  Many times these limits are a result of our own stack space limits, so it would be interesting to see what workload this was based on, and whether it still exists.

https://github.com/llvm/llvm-project/pull/143785