Rename legacy environment error monad fail
Following the merge of !6844 (merged), the environment exports syntax modules where fail/tzfail determines whether the error is wrapped in a trace.
The legacy fail function has the behaviour of the tzfail variant. This is confusing.
This MR addresses this by renaming the legacy fail function into tzfail.
Initial suggestion by @jobjo in !6844 (comment 1172998565)