rostests/kmtests/kmtest_drv/kmtest_standalone.c: "static IrpHandlers[]" and "static MessageHandlers[]" are never cleaned up

(Noticed while looking at ROSTESTS-264.)

kmtest_standalone.c

  45 #define KMT_MAX_IRP_HANDLERS 256

  46 static KMT_IRP_HANDLER_ENTRY IrpHandlers[KMT_MAX_IRP_HANDLERS] = { { 0 } };

  47 #define KMT_MAX_MESSAGE_HANDLERS 256

  48 static KMT_MESSAGE_HANDLER_ENTRY MessageHandlers[KMT_MAX_MESSAGE_HANDLERS] = { { 0 } };

NB: Feature added in r52550 (by ThFabba).

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IrpHandlers grep
Declaration, Add, Remove and Dispatch are supported.

KmtRegisterIrpHandler grep
1 call (from PoIrp_drv.c) + 2 calls (from Example_drv.c) + 17 other calls.

KmtUnregisterIrpHandler grep
(Only) 1 call (from PoIrp_drv.c).

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MessageHandlers grep
Declaration, Add, Remove and Dispatch are supported.

KmtRegisterMessageHandler grep
1 call (from Example_drv.c) + 4 other calls.

KmtUnregisterMessageHandler grep
No call.

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It looks like we miss either/both of:
*Matching KmtUnregister* calls for all KmtRegister* calls.
*Detecting/Doing this automatically (after each test sub-driver is stopped).

If, indeed, calling KmtUnregister* is (usually) unneeded, then that should be documented.