chore: add missing ensureSubscriptions call

[fbarbu15]

Problem

Saw a test failing on nwaku side because nwaku was missing ensureSubscriptions call

Solution

Added the call wherever it was missing

[github-actions]

size-limit report 📦

Path	Size	Loading time (3g)	Running time (snapdragon)	Total time
Waku core	27.81 KB (+0.27% 🔺)	557 ms (+0.27% 🔺)	1.4 s (-6.49% 🔽)	1.9 s
Waku Simple Light Node	262.86 KB (0%)	5.3 s (0%)	5.9 s (+4.12% 🔺)	11.2 s
ECIES encryption	29.69 KB (+0.45% 🔺)	594 ms (+0.45% 🔺)	2.6 s (+1.55% 🔺)	3.2 s
Symmetric encryption	29.69 KB (+0.45% 🔺)	594 ms (+0.45% 🔺)	2.9 s (+32.16% 🔺)	3.5 s
DNS discovery	110.58 KB (-0.06% 🔽)	2.3 s (-0.06% 🔽)	3.6 s (+1.07% 🔺)	5.8 s
Privacy preserving protocols	117.31 KB (-0.04% 🔽)	2.4 s (-0.04% 🔽)	4.8 s (+34.29% 🔺)	7.2 s
Light protocols	25.96 KB (+0.28% 🔺)	520 ms (+0.28% 🔺)	1.4 s (-21.34% 🔽)	1.9 s
History retrieval protocols	25.13 KB (+0.31% 🔺)	503 ms (+0.31% 🔺)	1.5 s (+11.18% 🔺)	2 s
Deterministic Message Hashing	5.65 KB (0%)	113 ms (0%)	757 ms (+25.2% 🔺)	870 ms