fix(rollup-plugin-lwc-compiler): Removing any COMPAT code on DEV

[diervo]

Details

Adding branch check to avoid sending polyfills in other modes.

Does this PR introduce a breaking change?

• No

[salesforce-best-lwc-internal]

Benchmark comparison

Base commit: c89c20b | Target commit: c112ff4

benchmark	base(c89c20b)	target(c112ff4)	trend
table-append-1k.benchmark:benchmark-table/append/1k	285.20 (± 9.13 ms)	268.57 (± 7.60 ms)	👍
table-clear-1k.benchmark:benchmark-table/clear/1k	14.68 (± 0.64 ms)	14.93 (± 0.67 ms)	👌
table-create-10k.benchmark:benchmark-table/create/10k	1555.89 (± 36.16 ms)	1499.61 (± 42.09 ms)	👍
table-create-1k.benchmark:benchmark-table/create/1k	164.91 (± 1.90 ms)	155.06 (± 2.25 ms)	👍
table-update-10th-1k.benchmark:benchmark-table/update-10th/1k	152.28 (± 6.29 ms)	138.47 (± 2.97 ms)	👍
tablecmp-append-1k.benchmark:benchmark-table-component/append/1k	365.19 (± 5.41 ms)	343.33 (± 9.98 ms)	👍
tablecmp-clear-1k.benchmark:benchmark-table/clear/1k	37.10 (± 1.20 ms)	34.81 (± 1.82 ms)	👍
tablecmp-create-10k.benchmark:benchmark-table-component/create/10k	2714.27 (± 35.76 ms)	2495.70 (± 15.89 ms)	👍
tablecmp-create-1k.benchmark:benchmark-table-component/create/1k	305.65 (± 11.89 ms)	274.68 (± 6.72 ms)	👍
tablecmp-update-10th-1k.benchmark:benchmark-table-component/update-10th/1k	153.52 (± 7.32 ms)	140.66 (± 3.97 ms)	👍