Bluetooth: host: Move auto-initiation of peripheral conn param update

Move auto-initiation of the peripheral connection parameter update,
this handling would only submit the delayed work with the timeout once
all other auto initiated procedures had completed. This behavior means
that the delay would not be set on when the connection was established
but instead relative to the previous procedures.
Based on the connection interval used, the instant(s) used, and the
number of auto procedures this delay becomes indeterminate.

Submit the work once connected, the constraint that existed in the
zephyr link layer earlier about requesting only one control procedure
at a time has been removed.

This also brings all the handling of the timeout work to the connection
state handling, which makes it easier to track this behavior in code.

Signed-off-by: Joakim Andersson <joakim.andersson@nordicsemi.no>