remove side effect imports

[Feiyang1]

Side effect imports cause some issue in the compilation since we use moduleSideEffects: false in the rollup config. The rollup flag won't be necessary once we get out of the exp phase, so we can change it back to the original way once that happens.

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Latest commit: 8f5496c

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Binary Size Report

Affected SDKs

• @firebase/firestore/exp

  Type	Base (41ed6f2)	Head (dfffb8b)	Diff
  browser	188 kB	189 kB	+271 B (+0.1%)
  main	467 kB	468 kB	+473 B (+0.1%)
  module	188 kB	189 kB	+271 B (+0.1%)
  react-native	188 kB	189 kB	+272 B (+0.1%)

• @firebase/firestore/lite

  Type	Base (41ed6f2)	Head (dfffb8b)	Diff
  browser	64.3 kB	64.6 kB	+276 B (+0.4%)
  main	142 kB	143 kB	+463 B (+0.3%)
  module	64.3 kB	64.6 kB	+276 B (+0.4%)
  react-native	64.4 kB	64.7 kB	+280 B (+0.4%)

Test Logs

• Base (41ed6f28): https://github.com/firebase/firebase-js-sdk/actions/runs/198686977
• Head (dfffb8bf): https://github.com/firebase/firebase-js-sdk/actions/runs/199467932