Disable ink-waterfall CI step 🦖

[ascjones]

paritytech/ink-waterfall#41 means that ink-waterfall always fails. This PR disables it until we can fix it so we can have a passing CI

[codecov-commenter]

Codecov Report

Merging #1509 (7fcbad2) into master (300b6c4) will decrease coverage by 6.59%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1509      +/-   ##
==========================================
- Coverage   71.60%   65.00%   -6.60%     
==========================================
  Files         204      204              
  Lines        6304     6304              
==========================================
- Hits         4514     4098     -416     
- Misses       1790     2206     +416     

Impacted Files	Coverage Δ
crates/ink/ir/src/ir/contract.rs	0.00% <0.00%> (-100.00%)	⬇️
crates/ink/ir/src/ir/ink_test.rs	0.00% <0.00%> (-87.50%)	⬇️
crates/ink/ir/src/ir/trait_def/mod.rs	0.00% <0.00%> (-81.82%)	⬇️
crates/ink/ir/src/ir/storage_item/mod.rs	0.00% <0.00%> (-73.92%)	⬇️
crates/ink/ir/src/ir/storage_item/config.rs	0.00% <0.00%> (-73.34%)	⬇️
crates/ink/ir/src/ir/blake2.rs	20.83% <0.00%> (-58.34%)	⬇️
crates/ink/ir/src/ir/trait_def/config.rs	7.14% <0.00%> (-57.15%)	⬇️
crates/ink/ir/src/ir/trait_def/item/trait_item.rs	45.90% <0.00%> (-45.91%)	⬇️
crates/ink/ir/src/ir/config.rs	64.00% <0.00%> (-36.00%)	⬇️
crates/ink/ir/src/ir/utils.rs	57.40% <0.00%> (-35.19%)	⬇️
... and 19 more

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