fix(press): delta pressure calculation before adirs on

[mjuhe]

Summary of Changes

This PR fixes an issue with the pressurization system. When spawning at an airport high above sea level the delta pressure was not being calculated correctly and the safety valved opened (triggering the corresponding ECAM warning).

The pressurization system uses the outside static pressure from the ADIRS to calculate delta pressure. Before the system is powered, the delta P cannot be computed. Now before ADIRS power up, the ECAM system page shows "XX" for delta pressure, no warning comes on, and the safety valve does not open.

Screenshots (if necessary)

References

Additional context

Discord username (if different from GitHub): Commander Ga

Testing instructions

Spawn at an airport high above see level (KDEN for example). Before powering up the ADIRS, ensure the delta pressure is not shown on the ECAM (it shows "XX" as above). Observe the safety valve is closed and no warrning comes on.

When setting the ADIRS to align, after a few seconds the delta pressure indication comes on, and is 0.

How to download the PR for QA

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4. Click on either flybywire-aircraft-a320-neo or flybywire-aircraft-a380-842 download link at the bottom of the page