Ever since #6162 we've had a mechanism in the UI to re-announce every 10
seconds that an apply is ongoing, for resource types that take more than
10 seconds to complete their apply.

Based on feedback that these messages are making the output too verbose,
it seems like 10 seconds is too short a duration to consider an operation
to be "unusually slow", or else these messages would not appear often
enough to be material.

With that in mind, as a compromise here we reduce the frequency of these
updates to every 25 seconds instead, which is another mostly-arbitrary
number but one that aims to strike a compromise between being long enough
that _most_ operations will not take this long, but short enough to keep
the UI output coming for long-running operations so that users can be
reassured that Terraform is still working and not hung, as seems to have
been the motivation in #6162.