Trying to migrate the wiredtiger-test-format-stress jenkins job to evergreen using format wrapper script(format.sh) but it fails to find the "wt" binary because it is tightly coupled with the relative path.

Steps:

1. Execute format.sh from "wiredtiger/build_posix" directory  ../test/format/format.sh -n 10 -t 5 -j 16 -v
2. The find_file() method of format.sh script finds and sets the format_binary to  "../test/format/../../build_posix/test/format/t"
3. Test format binary "t" internally tries to execute "wt" binary (../../wt) and fails as it cannot find.

The simplest solution is probably to change directories in the format.sh script. Changing directories means we'll need to either require the -h option (and the -h argument has to be an absolute path name), or we'll have to acquire the full path of the target directory before changing directories. It also means we probably can remove the work in format.sh to find the wt binary.