Bump opentelemetry-cpp version to 1.9.1, change LogExporter/LogProcessor to post-1.6 LogRecordExporter and LogRecordProcessor

[niande-xbox]

What? The fluentd exporter lacks breaking changes around the naming of Log classes (which changed to LogRecord classes).

Remove -DWITH_fluentd option that seems deprecated now.

What will this enable? This should enable adding opentelemetry-fluentd to vcpkg, since the opentelemetry-fluentd port depends on opentelemetry, so we need to be compilation-compatible with the latest version, which is 1.9.1.

What validation have I run? I've been able to see my changes in my own fluentd server:

023-06-20 19:46:35.296130644 +0000 Log: {"ObservedTimestamp":1687290395,"Timestamp":null,"body":"f2","severityNumber":5,"severityText":"DEBUG"} 2023-06-20 19:46:35.296328136 +0000 Log: {"ObservedTimestamp":1687290395,"Timestamp":null,"body":"f3","severityNumber":5,"severityText":"DEBUG"}

I've also passed the gtests:

I also repeated the build and gtest-suite on a fresh Ubuntu-20.04 VM.

[linux-foundation-easycla[bot]]

The committers listed above are authorized under a signed CLA.

• :white_check_mark: login: niande-xbox / name: Nick Anderson (bf3c5c656ec3834d592378c27bf03b52a58db3c0, 41f09382c53149ab419013d318635d27cad5c80c, 3cf83be97957baa9d0c7b76dcf154a0d11aead90, d421a6efaddefa581beceae3ef819a0d29572433, b15307b299fb0817db95be3bf6ae9b497ac682ca, afb11f10da8309400177b094f96cd230428c7fec, c683ba22257bbe3f7fe88c979959815c1918a380, d5b0464a1805797516a89d23a1a9548b38657113, 3c7e9120762cb5f25491402a5ccdd6443a101907, 8c536fd98c96411c34e3186d13b26e9973e74bc4, 8dd8285b3d240888f7f81e205c75280d5319d6ef, 950809688c2111d20329a9bb783eb9114ab5e2d7)