xpay: don't try to timeout things until after we have created xpay layer.
```
lightningd-1 2024-11-19T05:21:16.313Z DEBUG lightningd: Looking for [askrene,layers]
lightningd-1 2024-11-19T05:21:16.314Z DEBUG lightningd: Got [askrene,layers,xpay]
lightningd-1 2024-11-19T05:21:16.314Z DEBUG lightningd: Printing
lightningd-1 2024-11-19T05:21:16.315Z **BROKEN** plugin-cln-xpay: askrene-age failed with {\"code\":-32602,\"message\":\"layer: Unknown layer: invalid token '\\\"xpay\\\"'\"}
lightningd-1 2024-11-19T05:21:16.318Z DEBUG plugin-cln-askrene: datastore = {\"datastore\":[{\"key\":[\"askrene\",\"layers\",\"xpay\"],\"generation\":13,\"hex\":\"000300001000003f47af0100000000673c1fea010000000000d1b0d4000003000000000ce5066e0000000000673c1fea010000000000d1b0d400000300001000001a47050000000000673c1fea010000000000d1b0d400000300003f00005a72b40100000000673c1fea010000000000d1b0d400000300000000005a07e80100000000673c1fea010000000000d1b0d400000300001a0000e3564c0100000000673c1fea010000000000d1b0d40000030000e3000db69cf50000000000673c1fea0001000000000100637e\"}]}
lightningd-1 2024-11-19T05:21:16.318Z DEBUG plugin-cln-askrene: Loaded level xpay (203 bytes)
lightningd-1 2024-11-19T05:21:16.391Z INFO plugin-cln-xpay: Killing plugin: exited during normal operation
```
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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