test: autoloop test flake

[bhandras]

Found this flake using the CI build.

    autoloop_testcontext_test.go:271: 
        	Error Trace:	autoloop_testcontext_test.go:271
        	            				autoloop_test.go:601
        	Error:      	Not equal: 
        	            	expected: 80000
        	            	actual  : 160000
        	Test:       	TestAutoLoopInEnabled
    autoloop_testcontext_test.go:271: 
        	Error Trace:	autoloop_testcontext_test.go:271
        	            				autoloop_test.go:601
        	Error:      	Not equal: 
        	            	expected: 160000
        	            	actual  : 80000
        	Test:       	TestAutoLoopInEnabled
    autoloop_testcontext_test.go:310: 
        	Error Trace:	autoloop_testcontext_test.go:310
        	            				autoloop_test.go:601
        	Error:      	Not equal: 
        	            	expected: &loop.LoopInRequest{Amount:80000, MaxSwapFee:1000, MaxMinerFee:500, HtlcConfTarget:10, LastHop:(*route.Vertex)(0x1c522e0), ExternalHtlc:false, Label:"[reserved]: autoloop-in", Initiator:"autoloop", Private:false, RouteHints:[][]zpay32.HopHint(nil)}
        	            	actual  : &loop.LoopInRequest{Amount:160000, MaxSwapFee:1000, MaxMinerFee:500, HtlcConfTarget:10, LastHop:(*route.Vertex)(0xc000044e40), ExternalHtlc:false, Label:"[reserved]: autoloop-in", Initiator:"autoloop", Private:false, RouteHints:[][]zpay32.HopHint(nil)}
        	            	
        	            	Diff:
        	            	--- Expected
        	            	+++ Actual
        	            	@@ -1,3 +1,3 @@
        	            	 (*loop.LoopInRequest)({
        	            	- Amount: (btcutil.Amount) 80000,
        	            	+ Amount: (btcutil.Amount) 160000,
        	            	  MaxSwapFee: (btcutil.Amount) 1000,
        	            	@@ -6,3 +6,3 @@
        	            	  LastHop: (*route.Vertex)((len=33) {
        	            	-  00000000  01 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
        	            	+  00000000  02 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
        	            	   00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
        	Test:       	TestAutoLoopInEnabled```

[arshbot]

note: the following oneliner is useful for hunting this flake

while /usr/bin/go test -count=1 -timeout 30s -run ^TestAutoLoopInEnabled$ github.com/lightninglabs/loop/liquidity; do :; done

[arshbot]

Looks like this flake was introduced by the initial test, maybe we should add a flake hunting step in our ci @bhandras? Just run every test 20 times or something?