Do not adjust minimum connection interval

When adjusting connection interval values, we used to increase both
min and max values to the minimum prefered values, which was tuned for
A2DP.

Now, with LE Audio, we would set the ecosystem base interval instead,
which lets the controller select right value from the range that remote
prefers.

However, if we set ecosystem interval to 10ms, but set both min and max
values to 11.25ms, we don't give the controller any room to adjust when
LE Audio capable device starts streaming. If we leave min value
unadjusted, then controller might be able to pick 10ms if it's in range
between min and max.

Bug: 300251578
Bug: 346960036
Test: m  -j32;
Flag: l2cap_le_do_no_adjust_min_interval
Change-Id: Iec321f52f6c3e0b273e9fb9fc3f8e4db9ffc0017