try to optimize getting all controllers

[jreidinger]

Problem

Getting zfcp controllers is very slow call.

Solution

Try thread approach without dbus calls for this specific http call.

Testing

original time on our testing s390

real    0m10.851s
user    0m0.005s
sys 0m0.005s

[coveralls]

Pull Request Test Coverage Report for Build 11243278108

Details

• 0 of 30 (0.0%) changed or added relevant lines in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.07%) to 70.523%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
rust/agama-lib/src/storage/client/zfcp.rs	0	30	0.0%
<!--	Total:	0	30	0.0%	-->

Files with Coverage Reduction	New Missed Lines	%
rust/agama-lib/src/storage/client/zfcp.rs	1	0.0%
<!--	Total:	1		-->

Totals
Change from base Build 11209402098:	-0.07%
Covered Lines:	15836
Relevant Lines:	22455

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💛 - Coveralls