Allow large strings in nvbench strings benchmarks

[davidwendt]

Description

Removes the 2GB limit check from the strings benchmarks and adjusts the parameters to be consistent across the benchmarks.
The default parameters will still not exceed 2GB for automation purposes.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[davidwendt]

/merge