[ci] fix path to branchClassification.yml (#10519)

When cherry-picking the commit, I noticed:

    Updating 61674e1..e04201b
    Fast-forward
    .../policies/branchClassification.yml\342\200\216"          | 13 +++++++++++++
    1 file changed, 13 insertions(+)
    create mode 100644 ".azuredevops/policies/branchClassification.yml\342\200\216"

`\342\200\216` indicated some weird invisible character!

I must have done this when copy-pasting the file path from GitHub's
web UI?

Rename the file to the correct name:

    Changes to be committed:
        renamed:    ".azuredevops/policies/branchClassification.yml\342\200\216" -> .azuredevops/policies/branchClassification.yml

Author: jonathanpeppers