[8.16] [ML] Trained Models: fix NaN in a progress bar during the download task initialization (#201221)

[kibanamachine]

Backport

This will backport the following commits from main to 8.16:

• [ML] Trained Models: fix `NaN` in a progress bar during the download task initialization (#201221)

Questions ?

Please refer to the Backport tool documentation

[elasticmachine]

:green_heart: Build Succeeded

• Buildkite Build
• Commit: afe5153c87427d73ef6ecee9700d4cb74a61879c

Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
ml	4.5MB	4.5MB	+6.0B

cc @darnautov